Bizarre Sexual Dimorphism

• Sonic X: The males of the species Cosmo belongs to (referred to as "Seedrians" by fans) resemble trees, while the females are more dainty and flower-like.
• Discussed early on in Dragon Ball: Soon after meeting, Bulma discovers that Goku's tail is real, and he rationalizes it by claiming that she doesn't have a tail because she's a girl. She briefly admits to herself that he might be right, as she's never actually seen a boy naked, but thought it was just "that other thing". Goku then mentions that his grandfather Gohan didn't have a tail, though he immediately qualified it by saying that he was a really strange guy.
• This appeared to be the case for the plants in Trigun, with the girls in bulbs with the big strange eyes and all, and the only two guys walking around looking like blond men. But later manga material shows that Vash and Knives really are different because they're mutants (probably throwbacks; the odds that the people who engineered the plants didn't use human DNA are vanishingly small), because some female independents come from space; the twins are just even weirder. Although, some like Cronica who appears at the end of the story, she looks like a Claymore, pale skin, blonde hair and is beautiful.
• Seton Academy: Join the Pack! is a world of talking animals. The males of any species are just upright, talking animals. The females are portrayed as Kemonomimi, which can lead to odd sights like a regular-sized schoolgirl and a colony of talking naked mole rats.

• Green Lantern: The Zamarons and the Guardians of the Universe. The Zamarons◊ are the female member of the race, and they look like human women. The Guardians◊ look like blue midget old men with white hair. They used to be identical, but the two races separated and continued to evolve (without reproducing…) into their present form. The Zamarons were later retconned to have always been blue-skinned, black-eyed, hairless, and almost noseless◊ (think tall, blue, female Roswell Greys). And they are still almost three times the size of the Guardians, so the trope still applies, since the two are either the same species or offshoots of the same species, Depending on the Writer.
  • The small size of the Guardians compared to the Zamorians and Krona was revealed to be caused by specific bandage wraps that the guardians used for restoration. Once Krona used them, he looked just like the Guardians. He also attempted to use them on Hal Jordan and Guy Gardner into guardians... somehow.
  • Even more confusingly, there are also female Guardians who look like Guardians. They originally came to be when Kyle Rayner (possessing at the time the godlike powers of Ion) recreated the Guardians years after Hal Jordan (at the time possessed by evil entity Paralax) wiped them all out. Of course in the current series all this is ignored and the Guardians are shown in flashbacks to have been always both sexes.
  • There are also the Controllers, who were also the same species as the Guardians/Zamarons, but appear to be tall, bald humanoid men with orange skin. It's safe to say that the whole species is just weird.
• In Legion of Super-Heroes, male Dryads look like large masculine-seeming humanoids made of stone. In some continuities, female Dryads look like large masculine-seeming humanoids made of crystal. (In others they look like the male dryads with narrower waists and Non-Mammal Mammaries.)
• Used as a twist ending in Alan Moore's Omega Men backup story "Vega: A Man's World" — the enormous grazing mollusks the all-male Culacoans "hunt" are actually stimulated to produce new males when prodded hard enough in a certain area, and split into two new females after seemingly dying. The difference in mating rituals is so vast that when Mopi tries to help a foreign anthropologist understand "gamugha", he innocently kills her with his spear. To quote the gamebook, "This seems to work for them."
• Wonder Woman Vol 1: The Rykornian females are large stationery stalks with long leaf tentacles, "sap" that drugs people into near unconsciousness, husks from which their smaller kin are born and in which they subsequently live, and do not speak nor have faces but have some degree of sentience. The ambulatory Rykornian males are small rhombus shaped beings with pyramid shaped heads, four thin leaf-like limbs and corn-silk like "hair" on their faces.

Marvel

• The Badoon, a Marvel Universe alien race, have scaly reptilian males and fur-covered females. The females are also stronger and tougher, but less violent and cunning than the males, and the sexes don't interact except during their once-in-a-lifetime mating frenzy. The females also have Non-Mammal Mammaries, despite laying eggs, though it's possible that they do suckle their young.
• Rom: Spaceknight's enemies, the Dire Wraiths, come in two flavors: the technology-using males, who look like ugly, fanged, gangly-limbed Pillsbury Doughboys; and the sorcery-using females, who are pure Starfish Aliens. The Dire Wraiths are eventually revealed to be offshoots of the Skrulls. For a race of shapeshifters, appearance isn't that important.
  • Technically, the true male Wraith form has never been seen since all male Wraiths have so far only been depicted in either assumed forms (while posing as humans or other species) or in their "transitory shape" which was once specifically stated to not be their true form. The fact that a group of female Wraiths once stated that they, unlike the male Wraiths, were not ashamed of the way they looked is considered to strongly imply that the true male form resembles (or is even identical to) the true female form. However, this theory has never been confirmed in any story.
  • Similarly, the reason why the Dire Wraiths look so different from the Skrulls has only been vaguely explained. One story claims that their Skrullian Deviant ancestors just happened to "mature" into two different strains. Another source claims that the Dire Wraiths look different because their ancestors began practicing black magic that, over generations, caused them to evolve into a different form that was less humanoid.
  • Male Wraiths generally used technology because the females had usurped sorcery for themselves.
• Spider-Woman Jessica Drew can't shoot webbing but her younger brother and occasional foe Michael can. That's because the spider species that makes up a good chunk of her spider DNA mix, only the males produce webbing, so Jessica was a bit miffed at her brother's extra ability.
• According to Word of God this was intended with X-23's claw arrangement. The foot claws were to be the result of how gender affects a mutant with the Wolverine-style mutation of bone claws and Healing Factor, with the claws in her hands for hunting prey, and her foot claws for self-defense.

Other

• Somewhat inverted in Disney's Donald Duck Comics. While in most real duck species, males have brighter colored feathers than females, nearly all of the ducks in the comics are white and gender differences are only visible in clothing and eyelashes.
• Male Warlocks from Nemesis the Warlock walk on a pair of goat-esque hooves, while females have centaur-like bodies.
• In Phil Foglio's XXXenophile:
  • Huldra (female trolls), in the story A Beautiful Tale, were scary-powerful Cute Monster Girls with cute little shark teeth and long tufted prehensile tails. We never actually see a male troll... but a human character who has infers that humans must not look dimorphic at all to trolls. (She's wrong; the huldra is fully aware that she's female and still wants to marry her. With all that that implies.)
  • In another story, Martians have females who have four arms but otherwise look like attractive humans. Males are small, furry, and non-sapient. They're a bit confused by the sapient male human they encounter (which doesn't stop them from having sex with him, of course), and easily tricked into believing that a twenty-foot-tall set of Powered Armor is a human female.
• In Proof (2007), we have the European Fairy. Females more or less resemble the classic fairy; a tiny (inches-high) green-skinned humanoid woman with pointy ears and two pairs of fly-like wings. Males are gargantuan blue-skinned Horned Humanoids who are about three or four times the height of humans. Females are malicious and voracious little monsters that must consume 50 times their own body weight in food on a daily basis, preferring meat, whilst males are docile, passive, and virtually sessile due to suffering from hemochromatosis. Females are much more common than males, and are the sexual aggressors in mating; males usually don't even feel the female copulating with them. After mating, the female gnaws her way inside of the male's body and consumes him from the inside out to feed her growing brood, leaving behind a hollow, porcelain-like husk that rapidly crumbles into dust. The pregnant female becomes massively swollen with eggs, and when she is near her term, her fellow females with violently kill her, stabbing her before disemboweling her to release the eggs into the wind, where they will promptly hatch into tiny infant fairies — at this stage, males are also winged. Most of the larval faeries will be eaten by birds or other predators, with the survivors growing up to repeat the cycle.
• Witches and Warlocks in Orange Crows at first appear analogous to human women and men, but there are unexplained differences in their physiology. Witches are female humanoids born with small, flightless wings on their lower backs. Only Witches are capable of casting magic or using mana to operate magic tools like a flying broomstick. Warlocks are wing-less male humanoids, distinguished only by their Pointy Ears. They can't use magic the way Witches can, but they do have a "craft" individual to each Warlock that appears to augment their body for combat.

• In Ben 10 fanfic Hero High Sphinx Academy, Alex reveals that Nicole is actually a hybrid of a rare alien that has the ability to heal virtually any injury and her skills can be used to save Ren. Ben then calls Alex out on this because he states he could have just turned into said alien and avoided all of this. Alex reveals that this ability is only found in the females of their species, whereas Ben can only turn into the males of that species.
• According to Word of God on Hivefled's interpretation of Homestuck troll biology, the trolls we actually see walking around are all chromosomally male. The enormous egg-laying Mother Grub is the only female. The difference between male-appearing and female-appearing trolls is more like that between worker and drone bees; the "females" have a large internal pouch in the place a uterus would be (crudely known as a "gutbucket") for carrying genetic material to the Mother Grub, and venom sacs for defending themselves during the long pilgrimages this entailed.
• Intelligence Factor:
  • Male Kangaskhan joeys never reach adult size, and become Marowak when their mothers die. However, there are just as many stunted female Kangaskhan as well.
  • Grimmsnarl and Hatterene are different sexes of the same species; the former looks like a goblin, and the latter looks like a witch, but they both have jelly-like hair.
• In Romance and the Fate of Equestria, the changelings are depicted as Bee People, and as such have sexual trimorphism. There are males, females, and queens, Queen Chrysalis being the only living queen and the other changelings seen in canon being females. Males are a creation of the author, being smaller than queens but much larger than females, have comically oversized wings, bull horns which work magic in the same way as a unicorn horn, and produce magical silk from their nostrils.
• In With This Ring, this is invoked by M'gann in her Shapeshifter Default Form. She knows that females aren't allowed to look alien, which is why she goes out of her way to look as human as possible. She slowly grows more comfortable to look more alien and embrace her White Martian side.
  M'gann: It's okay for guys to look like ogres but girls need to look like girls.
• In The Bridge (MLP), Godzilla Junior and Raiga are male and female of the same species. According to Word of God, while a lot of their differences are due to Junior being a nuclear mutation and Raiga being a genetically and magically altered, some of it is due to this trope. Males are dark gray colored while females are blue colored, and males have three sets of dorsal spines while females only have one. If they'd been altered the exact same way, Raiga would also be slightly larger than Junior is.
• Equestria: Across the Multiverse has the mane six visit version of Terra presented in The Bridge with Twilight being a Godzilla. As mentioned above, she has the same sexual dimorphism as Raiga (minus the skin color, as Twilight is still lavender) with the added addition of, due to being an atomic mutation styled Godzillasaur, being slightly taller than Junior.
• The War of the Masters: Like real lizards, female Gorn have no obvious-to-humanoids secondary sexual characteristics. Rather, they're just significantly bigger than males: the huge Gorn Ambassador S'taass, who is well over two meters tall in Star Trek Online, is interpreted as female. (One of the 'verse's co-creators kept pet lizards.)
• The Smeet Series: Played with in the Sobrekt species. The main branch (who look like humanoid crocodiles) are identical in both sexes, with males being only slightly bigger. On the other hand, with the kryvtor subspecies (who look like humanoid velociraptors), males have feather crests on their heads and the tips of their tails while females don't.
• Kaiju Revolution
  • The Skullcrawlers Ramarak and Rokmutul have only moderate similarities to each other. The female Ramarak is a (relatively) small four-winged flyer and a long horn-like protrusion on her head while the male Rokmutul is a large landbound brute with a massive set of arms on his back and a crocodile-like head. Interestingly, the offspring they produce don't mature into their adult phase, suggesting that they're the reproductive caste of their species.
  • This appears to be the case with Varan and Komodithrax as the two of them are the same species with the male Varan being a small, gracial glider while the female Komodithrax is a large, quadrupedal land hunter but this isn't actually the case. These difference are actually the result of their species Adaptive Ability which caused them to change in these ways.
• In the Not Safe for Work My Hero Academia fic Blessings of the Goddess, humanity has this: only 1 in 20 people is male, who hardly ever surpass 5 feet in height, their reproductive system makes as much as half their weight and their digestive system is so atrophied they can only gain sustenance from human female milk. Women, in exchange, are commonly more than 6 feet tall, their breasts can easily be larger than their heads and they are always lactating, with some being able to produce more than 50 gallons (189 litres) of milk in one go.

• In Treasure Planet Doppler, a dog-like alien, ends up dating Captain Amelia, a cat-like alien, and their children in the epilogue are shown to be a litter of kitten-girls and puppy-boys. While this could be Gender Equals Breed, this trope is also a possibility. This possibility is made even more likely with the game Treasure Planet: Battle at Procyon, which features multiple dog-men and cat-women, but none of the reverse.

• In Attack the Block, a small, hairless alien attacks the main protagonists and is quickly killed by them. However, it's not alone, as soon hordes of much bigger aliens, with black, shaggy fur and glowing teeth start showing up all around the area. Turns out that the first small alien was in fact a female, and the rest were males following its scent... which the teen gangsters have unwittingly rubbed onto themselves and made them targets for the males!
• Evil Alien Conquerors; the male aliens look just like human males, but the females look... just plain weird.
• Godzilla:
  • In Godzilla Vs. Monster Zero, the female Xilliens all look exactly alike (which is to say, like actress Kumi Mizuno).
  • Godzilla (2014): The M.U.T.O.s. The male has four legs and wings but is relatively small in size compared to Godzilla (about the size of an eagle if Godzilla was human-scaled), while the female is Godzilla's size and has six legs but cannot fly. However, in a subversion, the two are pretty much identical in appearance and recognizable as the same species. This is very similar to real-life insects, especially parasitic wasps, fireflies, and lubber grasshoppers.
  • A straight example occurs in the unmade Godzilla film Godzilla vs. Redmoon, where two kaiju appeared named Redmoon (a sort of dragon-like monster with one eye) and Erabus (a glossy, tree-like monster). The JDSF lures the two together in the hopes they'll fight to the death, but instead it turns out they are respectively the male and female of the same species and they instead mate and produce a child. It goes From Bad to Worse when a greedy entrepreneur kidnaps, and accidentally kills, the infant, causing the parents to go berserk and rampage, which awakens Godzilla.
• In Logan Xavier posits that the arrangement of Laura's claws are this, likening her to a lioness: The front claws are for hunting, the rear claws for defense. This doubles as a Mythology Gag: As noted under Comic Books above, this was actually the intent of X-23 creators Chris Yost and Craig Kyle, and Xavier's lecture is drawn from their own remarks on the matter.
• In the goofy Mom and Dad Save the World, the nonhuman natives of Spengo have males with dog-heads and females with fish-heads.
• In 1953's Mysterious Mesa Of Lost Women Dr. Aranya injected members of the Theraphosidae family with human pituitary hormones. His subjects grew to the size of human beings and developed reasoning powers. He found he could telepathically command them. He transplanted their brains back into humans, granting them the capacities and instincts of the giant spider. His females proved near-indestructible, and might live hundreds of years. The males dwindled to dwarfish proportions.
• Star Trek Expanded Universe:
  • The first Deltan◊ we see is a bald woman in Star Trek: The Motion Picture.
    • The script and novelization to Star Trek II: The Wrath of Khan say that Jedda is a Deltan. He has hair and looks human.
    • The novelization of Star Trek IV: The Voyage Home would have you believe that this is a male Deltan. No other source corroborates this, and it can be assumed to be an error. The "male Deltan" is later established as an Efrosian, the only other seen member of the species being the Federation President in the Star Trek VI, due to reuse of makeup. In the Star Trek: Titan novels, the Efrosians come from "Efros Delta", so you could call them Deltans, but they aren't those Deltans.
    • Star Trek: Picard shows male and female Deltans looking like bald humans.
  • Downplayed with the Gorn. Rather than Non-Mammal Mammaries, female Gorn are distinguished by simply being bigger than male Gorn. Unfortunately Gorn also never stop growing until they die, so an old Gorn male could potentially be mistaken for a young Gorn female or vice versa.
• Star Wars:
  • Male Devaronians look like devils, hairless, with pointed teeth and large triangular horns. The females have hair, and dark circles where the males have horns. Culturally, both are also distinct: males, while devoted to their families, are often struck by wanderlust and wander the galaxy. Females tend to stay on Devaron and are highly industrious and politically minded. In Legends canon, they were also this trope, but in a different way.
  • Male Twi'leks have large bony bumps on their foreheads, whereas the females instead have normal eyebrows. The males also have Pointy Ears, while the females instead have small cones in place of their ears. The females also have human-looking teeth while most (but not all) males have pointed ones. This last one is cultural, though: it's common for male Twi'leks to file their teeth into points, and a male Twi'lek Jedi youngling who appears in two episodes of Star Wars: The Clone Wars noticeably has non-pointed teeth. The Mandalorian has an episode with a Twi'lek brother and sister who both have pointed teeth in the same style. ^note  There are also cases where a particular work in Star Wars doesn't display the standard sexual dimorphism and has both male and female Twi'leks appear the same. A good example is the MMO game, Star Wars: The Old Republic, where the males lack bony foreheads and have the same cone ears as females instead of the pointy elf ears.
  • Supplemental material revealed this to be the case with Sarlacs, the tongue and mouth visible from the ground being part of the female and the male being a subterranean parasite that devours and merges with the female until the mated pair spews eggs out into space to hatch on distant planets.
• In Zone Troopers, a group of American soldiers in WWII discover crashed aliens in Axis territory. The males are tall, pretty, blue-skinned Aryans. The females, as it's later discovered, are hairy bug-eyed mole people. Needless to say, the soldiers had a bit of a shock with that revelation.

• Dougal Dixon's After Man: A Zoology of the Future:
  • The bardelot, a carnivorous tundra living rodent, has female with dark fur and teeth like a saber-toothed tiger's, while the male lacks her fangs, is white, and looks like a hunchbacked polar bear.
  • The common pine chuck has bright red seed-eating males and dull green, insect-eating females.
  • The matriarch tinamou's females are large, turkey-sized ground birds. while the male is a wren-sized parasite that perches on her back, pierces her with his beak, and permanently feeds on her blood, eventually losing his wings and digestive system (similar to real-life anglerfish).
  • Groaths, descendants of mountain goats, have females with a single pyramid-shaped unicorn horn and males with large, flat shields on their faces.
  • The distarterops, a walrus-like aquatic rodent, has females with symmetrical tusks and males with one tusk that points out forward and the other pointing straight down.
  • Pittas, small rainforest birds, have males that are about three times the size of the females.
• Alien in a Small Town has bizarre sexual trimorphism. The alien Jan have three sexes. The male Workers are the bulk of the population – conical and the size of a car, with three stumpy legs and three tentacles at their apex, one ending in a bowling ball-like eyesphere. The female Matriarchs are physically similar except that they eventually plant themselves in one spot and grow to be the size of a mountain (becoming super-intelligent in the process). The sterile Warriors are bigger and faster than the Workers, with six arms ending in hooks, the eyesphere flush with the top of the body, and a giant fanged mouth in the side of the body.
• In Emperor Mollusk versus The Sinister Brain, female Lunans are typically ten-feet tall, have shaggy grey fur and have three to seven limbs on random parts of their bodies. Males on the other hand barely reach ten inches, have short fur and only possess two arms.
• The New Dinosaurs: An Alternative Evolution, another Dougal Dixon work, has the Dingum, a small theropod dinosaur where the female resembles a generic, unremarkable coelurosaur, but the male is smaller, quadrupedal, venomous and possesses a retractable sail on his back resembling a monarch butterfly's wing patterns, as warning coloration.
• In Book of the New Sun, Erebus and Abaia are Eldritch Abomination who are tentacled masses the size of mountain ranges. Their daughter-wives, the Undines, are beautiful albino Human Aliens that grow to be about the size of castles — making them miniscule in comparison. Protagonist Severian once fought a 13 year old undine and she was about the height of an exceptionally tall NBA player.
• The Khepri in Perdido Street Station and all of China Miéville's other Bas-Lag novels are an insect-like race with small non-sapient males resembling beetles the size of human heads and females that resemble red-skinned human women with a similar type of beetle forming their heads. They consider humans to have Khephri bodies and the heads of hairless primates.
  • In the sequel, The Scar, there is a race of mosquito people, the Anophelii, whose women are vampiric winged creatures that have fang-like protuberances that extend from their mouths to penetrate their victims. The extremely passive males have mouths that are described as being like anuses. Yeah. The females are incredibly strong, can fly and have a ravenous hunger that overwhelms any higher brain functions they might have, whilst the males are earthbound, vegetarian and quite intelligent.
• Terry Pratchett's Discworld:
  • Pictsies, tiny Bee People whose female breeders ("keldas") start out the same size as males, but grow twice as tall and spherically-fat after a lifetime of birthing hundreds of offspring. A kelda's rule over her clan is absolute, as she's mother to most and wiser than any. Which isn't saying much, as male Pictsies are impulsive and slow to think, even for a Proud Warrior Race (although there are rarely born smarter males who usually become Gonnagles). They'd probably all be dead without a kelda to keep them in line.
  • The Igor clan are human (just barely) and do it intentionally. Both male and female Igors are brilliant surgeons who incorporate body parts from corpses into themselves, and can look however they want. Males choose to look like the traditional scarred hunchback, and speak with a heavy lisp. Females (or Igorinas) however follow a different trope, and are quite lovely (though they often keep a nice-looking scar or stitch-mark to signify their heritage).
  • Inverted with dwarfs, who all present as masculine regardless of their sex. Notably, it's not only other species who can't tell the difference between a male dwarf and a female dwarf: dwarfs themselves regard sexual identity (especially feminine identity) as a very private matter, and only a dwarf's parents and spouse are meant to know their sex.
• In Larry Niven's Draco Tavern stories, all the Chirpsithra were female. There are males, but the Chirpsithra won't talk about them. In one of the stories, the Chirp males are revealed. They're the "red demons", essentially mindless beasts.
• In Frank Herbert's Dune series, Tleilaxu females have been genetically altered, and serve as their axlotl tanks, basically giant wombs on life support.
• The Edge Chronicles:
  • The Termagant Trogs. The dominant females are massive hulking bald Amazons. Their husbands are skinny, shrimpy and rather pallid creatures usually kept locked up. As if that wasn't weird enough... when the females come of age, they undergo an induced Metamorphosis from sweet, ethereal little redheaded girls into the aforementioned bald (and bad-tempered) Amazons. If they miss the associated ceremony, they're stuck in the juvenile form.
  • Female shrykes are sadistic humanoid birds of prey with deadly weapons and even deadlier claws and beaks. Male shrykes are small and frail, with dull plumage and duller personality, and usually take care of mundane tasks while the females wage war and enslave orphans.
• In Everworld, the Hetwan males are vaguely humanoid Insectoid Aliens, while the females are described as transparent bags of organs with wings. How they reproduce: Hetwan males tear the females apart and eat them, and new Hetwan form at the males' waist during the process. Ugh.
• Weird exception: with all the Starfish Aliens in Wayne Barlowe's Expedition, it's interesting to note that this trope is hardly used at all. Indeed, it's often hard to tell if the terms "male" and "female" even apply; many species are functionally hermaphroditic, and mating impregnates both individuals. The closest thing would be the female Sacback, who lives her adult life buried underground as her male counterpart roams around finding food for her. Other creatures make up for it by having bizarre life-cycles (the Emperor Sea Strider, a giant ocean-going beast starts out as a tiny bug-like flyer, for example).
• In Flatland, men are polygons (whose number of sides and symmetry indicates their social class) and all women are single lines — hysterical, dangerously sharp, and not too bright. (The blatant sexism and classism is a satire of the attitudes that people actually had when it was written, as explained in a foreword added by Abbot when people missed this.) Other details of their physiology, including how they reproduce, are never explained. In Flatterland (a 2001 sequel by Ian Stewart), it is implied that the females utilize the males in detaching a segment after sometimes folding the segment into a new shape with roughly the same number of sides as the male. The females are also confirmed to be multi-sided beings that are rotated into a third dimension, which just brings up even more questions, including already-answered questions, the answers to which were suddenly made invalid.
• John Varley's Gaea Trilogy features a dimorphic intelligent species in which the gas-inflated males are living blimps and the deep-diving females are organic submarines. They begin life as sexless, snakelike animals, then choose which adult sex to metamorphose into when their consciousness and race-memory emerges. Mating takes place at the ocean's surface, aside from which the two sexes never interact.
• The insect-like society depicted in Frank Herbert's Hellstrom's Hive had breeding-machine females not conceptually unlike the piggies.
• In InCryptid this crops up among certain species of cryptid.
  • The dragon species and the related human-appearing dragon princess species are actually male and female dragons. This played a part in enabling the female dragons to survive as they could hide among the humans after the male dragons were killed by the Covenant of St George. They have since been prolonging their survival by a form of parthenogenesis, but since the discovery of a male dragon, William, under New York, the species appears to be reviving.
  • The female wadjets are human-appearing, while the male wadjets resemble existing species of cobras. This enables the males to hide among non-sentient snakes (even in a zoo) while avoiding the Covenant.
  • For a while cryptozoologists thought the Ukupani were an all-male species, until they realized the females don't have a humanoid form and just look like giant sharks (the males can look like humans or a humanoid shark form).
  • Female Pliny's gorgons are human-sized, while males are around 7 or 8 feet tall. Most males don't venture into human settlements because of this.
• In Into the Drowning Deep, it's revealed near the end that all the sirens encountered so far during the novel are male. It turns out the female of the species is a single boat-sized monster that the males are desperate to keep sated.
• The Cygnans in the novel The Jupiter Theft had human-sized females and insect-like parasitic males that were permanently attached to the females.
• Known Space:
  • The Kzinti are catlike people, and while the males are of humanlike intelligence, the females are not. However, ancient Kzinti females were entirely sapient — their current state is the result of intentional breeding for unintelligent women, with the help of genetic engineering technology. That's what happens when you uplift a bronze age species. Strangely enough, Kzinti (in Man-Kzin Wars) consider the human sexes to be separate alien species, based on behavioral differences. A human female (Manrrett) is considered to have apparently faster reflexes, higher pain tolerance, and greater intellectual insight, than a human male (Man).
  • The Puppeteers, who are already fairly strange-looking, are a subversion. What they refer to as "females" are actually a different, non-sapient species with its own males and females; true Puppeteers are parasitoids, with both sexes sporting similar-looking genitalia used to deposit gametes in the flesh of a host "female".
  • Grogs. Adult females are large furry cones with mouths, which cannot move from the rock they attach themselves to. Young females are something like alien bulldogs, while males are akin to chihuahua, neither of which are sapient; males do not mature out of this stage. Adult females telepathically control the young into breeding, and use the same telepathy to force prey animals to leap into their mouths, since giant immobile cones aren't good at hunting.
• The Laundry Files: Unicorns are depicted this way in the novella Equoid. Males resemble extremely poisonous cone snails, while fertile females resemble cute, tiny horses. A fertilized female, with the male attached, eventually grows into a massive, gelatinous, immobile thing of no small sorcerous power, using the entranced little girl to draw in other humans for it to eat: one such experience was revealed to have traumatized H. P. Lovecraft for life. Worse, near the end of its spawning cycle, the fertilized female can think and speak.
• Tolkien's Legendarium:
  • The Lord of the Rings inverts the trope with the dwarf race, with it being stated that female dwarves are often mistaken for men due to being similar to the males in voice and appearance. As every male dwarf we encounter in the book has a prominent beard, some readers have interpreted this as meaning that the female dwarves even have beards.
  • In the films, this became a rather comedic scene where Gimli humorously explains this phenomenon to a human woman. The human woman (Éowyn) then turns around and looks at Aragorn to see if Gimli is pulling her leg, and he mouths, "It's the beards," and gestures at his chin. A few female Dwarfs in the crowd scenes of the Hobbit movies show a great variety of facial hair, anywhere from a thin fuzz or trimmed muttonchops to full braided beards.
  • Confirmed in The Silmarillion, which says "For the Naugrim have beards from the beginning of their lives, male and female alike."
• In Man After Man: An Anthropology of the Future, one species of post-Homo sapiens hominid developed the ability to hibernate. As males slept for most of the year, whereas females remained awake to nurse their young except in the depths of winter, the sedentary males wound up having a lifespan several times as long as that of the nomadic females.
• Medea: Harlan's World was a collaboration between a number of major SF writers to create a single setting, and a series of short stories set on the titular moon. In "Flare Time" by Larry Niven, the reproductive cycle of the native sentients known as fuxes is described. They start off as six-legged females. At around seven they have their first litter, during which their rear body segment tears off, leaving them as four-legged females. The hindquarters contain the eggs, and function as a nest which the newborns eat their way out of. Around seventeen they have a second litter, leaving them as two-legged males, with the male organs exposed through the loss of the second body segment. The male guards the nest until the young are born, then goes into heat for about three years, and eventually ends up a "post-male".
• Midnight Robber by Nalo Hopkinson has the douen, natives of the Penal Colony planet New Half-Way Tree. The males are lizard-like, and can speak fairly well. The women are more bird-like, with feathers and a beak which limits their ability to speak human languages — which is why most humans aren't aware they're intelligent, let alone the same species.
• In Dennis L. McKiernan's Mithgar series, dragons are the male of a species. What are the females? Of all things, krakens!
  • Dwarves are interesting. Only the males are seen by outsiders. Anyone that visits a Dwarvenholt that is considered friendly might catch a glimpse of a veiled, graceful figure that swiftly departs, said to be a "Chakkia" (the dwarves call themselves Chak). One character caught a glimpse of a Chakkia without the veils: she was beautiful. Another character, able to see the "true form" or light of living things, stated that he did not believe the Chakkia to be dwarves at all, their light was too different.
  • In another book, a seer also commented (to herself) that they were clearly not the same species as the male dwarves, then recognised them as... something else that she wouldn't tell us about, wondered if their state was some sort of divinely ordered punishment, and then claimed it was none of her business and turned away. If he keeps writing enough books he MAY explain all this.
• Subverted in Bruce Coville's My Teacher Is an Alien with Kreeblim, a female alien who looks very different to the previously introduced male one, Broxholm. The human narrator initially assumes this trope is in play, but it turns out that they are of completely different species.
• In the Paradox Trilogy, the xith'cal have genetically engineered themselves so that males and females are specialized for different tasks. Males are much larger and serve as warriors, while females are smaller and serve as scientists. Maturing xith'cal are able to choose which gender they will become, and may even decide to remain genderless, though doing so is uncommon.
• In Peter Pan fairies have sexual trimorphism. They glow one of three possible colors depending on their gender. Yellow fairies are female, white fairies are male, and blue fairies are "little sillies that don't know what they are."
• Jack Vance's Planet of Adventure: In The Dirdir, the titular Dirdir race has a complex sexuality. A male will be born with one of twelve different sex organs, females one of fourteen. Each type matches one or more of the others. Mating is complicated by the great secrecy surrounding sex: no-one wants to be "outed" as a particular sex since there are a host of restrictive sexual stereotypes waiting to be applied.
• Retief: In Retief and the Pan-Galactic Pageant of Pulchritude, an alien comments to Retief on the "remarkable sexual dimorphism" of Terrans, after Retief slips a ringer into the titular beauty pageant: a female Bengal tiger. The alien is apparently used to sexual dimorphisms extreme enough to make this plausible, and doesn't notice the difference between human males and females, except to suggest that the human with the large protrusions on his (actually "her") upper thorax might want to see a doctor about it.
• The Piggies and Buggers in Speaker for the Dead. Especially the piggies. The buggers are about as sexually dimorphic as real bugs. Both species call humans weird for having sexes so similar that both can perform the same societal function.
  • The piggies' life cycle and reproduction is strange enough that it really deserves to be explained in full detail (though put in spoilers). Both sexes start out small and grublike, but the dimorphism starts quickly. The males develop into the pig-like form that the humans in the story first assume were the only form, but will develop into enormous trees upon death and retain their sentience upon being ritually vivisected.
    
    The females, on the other hand, almost all stay small and grublike, and after a certain time are carried by the pig-like males to the trees, and are impregnated by said trees via pollen. Then, when the young they're carrying are ready to be born, they eat their way out of their mother. If a female is infertile, she will develop into a pig-like form like the males to serve as a matriarch, and can also be vivisected to become a "mothertree", which holds all the young and nourishes them with its sap. "Bizarre sexual dimophism" doesn't even begin to cover it.
  • There's also the apparently female-only deer-like creatures that are impregnated by the grass-like male half of the species. The xenobiologists spend half the book puzzled over evidence of genetic exchange (which implies the species don't reproduce by parthenogenesis like some earth species do), yet without any apparent presence of males.
    • This is all a relatively recent development from an evolutionary standpoint, caused by the Descolada, a highly-adaptable virus that literally unravels DNA strands. The only things that can survive it are those who have adapted to use it.
• In Sergey Lukyanenko's Spectrum (2002), the main character meets several members of a race of Reptilians (according to the book cover, they look like Narns). Later, his Love Interest explains that the non-sapient animals they travel with are actually their females, as she saw one of the aliens mating with one of the animals. That or bestiality. The cause for this appears to be an ancient cataclysm that affected all known races, causing many of the bizarre biological and psychological features of the aliens.
  • In Today, Mom there are genetically engineered sphinxes: lion-sized sentient beings created to survive on Venus to terraform it to human-habitable conditions. The males were working on Venus, the females were kept hidden on Earth. One day males revolted, declared independence and smuggled females to Venus. They were very shocked to learn that the females are ordinary, non-sentient domestic cats (artifical insemination is used). At one point a sphinx shows his family portrait with his mom and two sisters.
  • In Negotiators it's humans who are bizarre. Aliens cannot believe there can be such huge psychological differences between genders and disregard the information as savage chauvinism. But it's the habit to come to terms with people you don't fully understand, what makes humans the best negotiators.
• The Agletsch in Ian Douglas's Star Carrier novels are peaceful spider-like creatures whose hat seems to be information exchange (they don't even have colonies, just trading outposts). In the second book, it's revealed (to the readers, not the characters) that the "spider-like" Agletsch are, in fact, their females. The males are the tiny non-sentient slug-like parasites that all females carry attached to their bodies. The males feed off the females, but fertilize them for reproduction. This is first brought up when a racist maître d' of an expensive restaurant tries to kick out two Agletsch who come in, calling them "gentlemen". A main character corrects him, and points out they're "ladies".
• In the Steerswoman series, female demons are tall, spray acid from under their arms, and can make sculptures (out of a wax-like substance that their bodies produce). Male demons are much shorter and cannot make these sculptures. Since these sculptures are how demons communicate, this is a major social barrier.
• In David Brin's Uplift series:
  • In the Uplift Storm trilogy, male urs are much smaller than females, and generally less intelligent (though sapient; a male urs is a secondary character in the series). Females have pouches to carry their mate around.
• In David Gerrold's The War Against the Chtorr series, the bunnydogs/bunnymen and libbits were eventually discovered to be the male and female of the same species. It's heavily implied that the entire Chtorran "ecology" may not have the concept of "species" at all.
• The War of the Worlds: Global Dispatches story "Paris Conquers All" reveals that Male Martians have 3 arms and legs, and females have 4 (this however strongly contradicts the original War of the Worlds, in which the Martians are genderless)
• Bob Shaw's "Warren Peace" has the Squelchers, an alien race with no less then six different sexes, each one with its own unique appearance, and with a reproductive cycle where each sex fertilizes the others in turn. The forms look so different that, to the vast majority of the universe, the species only consists of the fourth sex, which resembles an orange haired saggy sasquatch (kind of like a blown up balloon that's developed a slow leak) with multiple eyes in a ring around its head (usually covered by its fur), oversized feet that let it wade on water, and two giant red nipple-like gamete sacs positioned one above the other on its torso. The fifth sex, the only other one mentioned, is described as being indistinguishible from a tree, except for the presence of a pair of two dual-pronged ovipositors (they look almost identical to staples) sprouting from its trunk.
• Well World: The Diviners and the Rels are the females and males of a single species, which in adulthood form into conjoined, symbiotic pairs. Rels resemble floating crystalline bowls with a set of wind chimes hanging beneath them, and provide movement, speech and sensory input for the duo. The Diviners resemble balls of moving lights carried in the Rel's bowl, can see into the future, and can fire beams that disintegrate whatever they touch.
• Theodore Sturgeon's "The World Well Lost" centers on a pair of fugitive "loverbirds" from the planet Dirbanu, which has shunned contact with Earth. The loverbirds are initially assumed to be a male and female, but they manage to explain, via some illustrations, that male and female Dirbanu are vastly different in appearance. In fact, the main reason why the Dirbanu dislike humans is due to homophobia, because they perceive all human relationships as being homosexual.

• This trope is played with in the first season of Farscape, where a Yenen named Staanz (played by a male actor) turns out to be an attractive female of the species.
• The Lord of the Rings: The Rings of Power: An Entwife can be distinguished from their male counterpart by the flowers covering their treetop. Winterbloom is covered in cherry blossoms, while Snaggleroot in leaves.
• The Outer Limits (1995): Downplayed in "Quality of Mercy". The male members of the hostile alien species are much larger than an ordinary human; the female members are a lot smaller. Which makes it more surprising when Cadet Bree Tristan turns out to be one of them.
• The Mers (essentially carnivorous seals from the future) from Primeval. The Mer Queen is about ten times the mass of a regular Mer (which can easily overpower a human). Fortunately, Mers, being big, not terribly fast, and lacking in any sort of natural armor, are particularly vulnerable to bullets.
• Ultraman Cosmos has the Giragas aliens, whom Cosmos battles in two different episodes. Males of the species are Ultraman-like humanoids with large claws and glowing eyes that behave like mindless brutes. On the other hand, the intelligent, bloodsucking females resemble a pair of wings with red eyes that live symbiotically on the males' backs, allowing them to fly.

• According to some traditions, the male equivalent of a mermaid is a "merrow". Merrows are hideous but friendly to humans, as long as said humans don't try to steal their wives. Of course, mermaids are hot, so humans try to steal their wives a lot, actually, thus incurring the merrows' wrath. In fact, lots of stories feature fugly (or at least Hollywood Homely) mermen and drop-dead gorgeous mermaids, probably because Most Writers Are Male. There are always exceptions, such as mermen of Scandinavian folklore (who tend to be Pretty Boys as a rule), and mermen featured in more modern works (especially those penned by and for women).
• Some legends claim the male griffin had no wings (and was called an opinicus).
• The kinnara (a legendary race in Hindu mythology) is a fine example of this. The females were human from the waist up, and birds from the waist down (kind of like a harpy, but not really) while the males had the lower half of a horse, in the same manner as a centaur!
• In Classical Mythology there is a monster archetype called the drakaina, which translates to "female dragon". While early depictions framed this as being exactly what they were, later ones depicted them as Snake People and often Cute Monster Girls, while male dragons were consistently portrayed as enormous deadly serpents. Likely also a case of Sexy Dimorphism.

• In The Dark Crystal, Gelfling females have wings; males don't.
  Jen: Wings? I don't have wings.
  Kira: Of course not. You're a boy.
• One sketch from The Muppet Show showed a mating.. er.. "Galley-oh-Hoop-Hoop ritual" of two natives of Planet Koozbane, and they looked nothing alike. (As an aside, the ritual involves the pair getting a running start, charging headlong at each other, colliding and blowing up.)

• John Finnemore's Souvenir Programme: The Anglerfish example (see Real Life) is spoofed when the head of a celestial project in charge of designing animals meets the guy who created puffins, and finds his newest creation: A hideously ugly fish designed to live in the abyssal depths, where it lures prey in with a light on its head. His boss is horrified by the creature, and even more so when he hears how it reproduces. Turns out the designer's just been dumped by his girlfriend, Angela, and he's taking it a little hard. Hence, the Angelafish.

• In Castle Falkenstein there are no female Dwarfs. Dwarfs always mate with Fairy women — if the child's male, it'll be a Dwarf like dad, otherwise, it'll be whatever sort of Fairy mom is. (There are male Fairies.) See Gender Equals Breed.
• Dungeons & Dragons:
  • The second edition Monster Manual implies that the Always Male satyrs and the Always Female nymphs are male and female of the same species.
  • Sphinxes have one type of female and three types of male: androsphinxes (male human head) gynosphinxes (female human head) criosphinxes (ram's head) and hieracosphinxes (hawk's head) of respectively Lawful Good, True Neutral, Chaotic Neutral and Chaotic Evil alignment. Gynosphinxes are Always Female, the others are Always Male. A gynosphinx mating with a hieraco- or criosphinx always produces hieraco- or criosphinxes as offspring, while if mating with an androsphinx they produce twins, one of which is a gynosphinx and the other an androsphinx. This means that, for obvious reasons, gynosphinxes don't like mating with crio- or hieracosphinxes much, which means that the Criosphinx has to convince the Gynosphinx to mate, whereas the evil heiracosphinx just rapes her. Androsphinxes on the other hand don't like mating much at all, meaning that in that case she has to convince him to mate, and it is noted that gynosphinxes will pay adventurers handsomely for the location of an androsphinx. This angle is dropped in 5e, which only has the gynoshinx and androsphinx and doesn't note either to take issue with mating.
  • There are also medusae, depending on edition:
    • Played straight in 2e, where the females have snakes instead of hair, with 10% being poison-blooded Snake People for added measure, and the males, called maedars, look more-or-less like bald human men. They also differ in terms of powers; females have a petrifying gaze, whilst males can walk through stone like it was air, are strong enough to smash rock with their bare fists with ease, and they can do Stone to Flesh by touch at will, unlimited applications per day. They use these two abilities to smash petrified creatures to bits (killing them) then convert the bits back to flesh for food. Needless to say, although they can breed with human men instead, medusae very much want one for a mate. However, maedar are extremely rare, to the point where their entry states that most in-universe experts think medusae are just an Always Female One-Gender Race, which means that the vast majority of medusae are forced to mate with human or demihuman men, which is fortunate for the species, as this is the only way for them to have medusa daughters, as mating with a maedar almost always produces human babies, aside from the very slight chance of a maedar baby.
    • The 3rd edition core setting basically states that medusae are an Always Female One-Gender Race, but Eberron claims that male medusae exist and, apart from the mammalian gender differences, are identical to females.
    • Played down in 4e, where male medusae are bald and have a venomous gaze, but are otherwise clearly related to female medusae, just like human men and women.
    • 5th edition takes the Eberron route; medusae come in male and female genders, both look like beautiful examples of their sex with snakes for hair, and both have a petrifying gaze.
  • In a non-canon third-party sourcebook, The Slayer's Guide to Troglodytes from Mongoose Publishing, the titular lizard-people are made up of sapient humanoid males and non-sapient females that look like huge bloated lizards.
  • Dragon: One of the first of the popular "Ecology of the ___" articles applied this trope to the catoblepas, a long-necked buffalo-like monster ugly enough to kill anything that sees its face. An in-universe naturalist reveals the solution to how such a deadly-to-approach creature can mate: the infamous quadruped is actually the female of the species, which grazes on water weeds in marshland. The male, a harmless bipedal grass-eater, spends most of the year on dry ground, but in breeding season he enters the marshes, locates a female by her scent, waits until she's dipped her lethally-hideous head underwater to graze, mates very quickly and then runs like hell. Offspring remain immune to the females' death attack just long enough to be weaned. This however was retconned away by the very next edition, as now the male looks the same as the female, and has the same death gaze too.
  • The four female Hulks of Zoretha are giant, rocky-skinned humanoids and entirely sexless by human standards, and have Elemental Powers. The male Hulk is a much smaller Winged Humanoid with a body perfectly matching human standards of male beauty, and can shoot poisonous spikes from his forearms.
• Humanoid cat warriors from Magic: The Gathering have, apart from breasts and hip shapes, one weird trait of sexual dimorphism: most female members are leopards or jaguars, while most male members are lions or tigers. The only exceptions are black panther warriors whose males and females are all black panthers (in real life, black panthers are actually just leopards or jaguars), and Leonins whose members are all lions.
• Steamlogic's Mechanical Dream has the Laudoling. The males are upright human-sized creatures that look like a mosquito got crossbred with a satyr while the female is a gigantic quadruped that looks a bit like a giant scorpion with no tail or pincers and a round helmet-like head. It's been speculated amongst academics, that the Laudoling were originally two different species (male Laudolings can mate with any living thing and the resulting offspring is almost always the mother's species, though some matings result in a male Laudoling offspring).
• In Myriad Song Rhax females look like roughly human sized spiders with two or four limbs adapted into arms, males look exactly like spiders that never get larger than a meter across and aren't sapient.
• Pathfinder:
  • Sphinxes. The gynosphinx produces offspring based on the emotional rapport she had with their sire. Encounters done for pure lustful pleasure produce crinosphinxes, The Power of Love produces gynosphinxes and androsphinxes, and hatred or resentment produces hieracosphinxes — which means they pretty much only occur as a Child by Rape. Unfortunately for gynosphinxes, they are naturally lusty, whilst androsphinxes are pretty apathetic towards sex, meaning that even if they do get an androsphinx to bed them, they're more likely to produce crinosphinxes than anything. Reading between the lines, the genuine affection and commitment that crinosphinxes show towards gynosphinxes means they are probably more likely to produce gynosphinx and androsphinx offspring, if the gynosphinx can get over her ego and learn to respect them back.
  • The Ceratoidi are Anglerfish-style Fish Men, Or rather Fish Women. Like the real anglerfish below, the female is the one most see, while males are the size of a rat, and attach themselves to the female.
  • Two classic RPG monsters, the trapper and the lurker above, were re-imagined for this game as the female and male (respectively) of a single species, the "lurking ray". The smaller, non-sentient males become capable of flight as they mature, allowing them to seek out the heavier, flightless, intelligent females. On top of that, juveniles of the species are Pathfinder's re-imagining of a third stock fantasy monster, the executioner's hood. Which makes sense, as they too hunt by wrapping around and smothering/crushing prey.
• In one of the many Star Trek role-playing games, Orions are presented as having green-skinned females and gold-skinned males. No canon source bears this out. On the live-action shows, no males are seen until Enterprise and they're all green. Many of the Expanded Universe sources present Orions as having a range of skin colors, but pretty much universally present males and females as having the same range of colors, which generally doesn't include gold. The one time their men were shown on the show they were basically the extreme of human dimorphism, all being huge and heavily muscled males or smaller and lithe females.
• The Talislanta game does this with not one, but two species:
  • In the first example, the stooped, wrinkled females are Gnorls and the gangly, monkey-like males are Weirdlings. The former live in elaborate cavern homes, while the latter live in simple burrows; they inhabit different regions, but come together every 50 years or so to mate. Both sexes were named separately by outsiders, who'd thought they were different races at the time, and no Gnorl or Weirdling will admit what (if anything) they call their mutual species.
  • In the second example, female Batreans are Green Skinned Space Babes, complete with hyper-seductive pheromones, while their male counterparts are grotesque, hulking ogre-ish creatures. The females are intelligent and live in Polynesian-style villages, while the moronic males shamble around in the jungle, looking for edible things to hit.
• The Skaven of Warhammer fantasy take this to extreme of the females being non-sapient and even more rat-like than the males — "breeders", as they are called, basically look like Ogre-sized or larger female non-anthropomorphic rats, made even bigger by the fact they are swollen so huge with litters that they can't walk. The last Codex seemed to show that there are normal-sized sapient females.

• The Grekim from Achron have three sexes (octo, pharo, and sepi). Octos crawl along the ground with six limbs out to the side like an insect or crab, with the remaining 2 held out front like arms. Sepis float slightly above the ground with their tentacles dangling beneath them. Pharos walk around with six limbs directly beneath them, and the other two out front. The changes in body types get even weirder with the 'higher' classes. Did we mention that they are all cyborgs and they use Time Travel as their weapon of choice? Starfish Aliens indeed.
• Orcs in Allods Online are dimorphic enough to give WoW's draenei and trolls a run for their money. The males are hulking, hunched brutes with huge tusks; the females are athletic-looking gray-skinned women with Cute Little Fangs.
• The Orfa, an alien race from Ascendancy, have a staggering 17 distinct sexes. The game theorizes that the only reason that they even evolved to sapience was the extreme sexual competition that arose from their ridiculously complicated mating system.
• In Breath of Fire, males of the Blacksmith Clan are hulking minotaurlike oxmen. Females look like human women with horns.
• On the MUD Dark & Shattered Lands, there's the Leonine race, which may just take the cake. The males are Wemics, basically centaurs with lions instead of horses. The females are Felars, pretty much just catgirls, which can have fur on as much as ninety or as little as ten percent of their bodies. Yes, the males are quadrupedal and the females are bipedal. Cue a huge number of off-color jokes...
• Darklands: Holzfrauen look like attractive women and are kind. The men of their species, the Schrat or wodewose, look like green-haired sasquatches and will try to steal female members of your party.
• Darksiders: The Makers are a race of giants with humanoid shapes. However, the males have disproportionally small heads compared to their massive bodies while females have balanced proportions.
• In Darkstalkers, Succubi are gorgeous women and nymphettes. 60% of Incubi, on the other hand, are gigantic mutant insectoid dragons.
• In Disgaea, male were rabbits are basically anthropomorphic rabbits. The females (Usalia and her mother) look human but with rabbit features.
• The Donkey Kong Country games tend to make female apes look more anthropomorphic than the male characters, typically having human-like proportions, walking upright and wearing clothing (Dixie Kong is the exception, since she essentially looks like Diddy Kong with a wig).
• In Dota 2 there are two representatives of the Slithereen race, living underwater. The females look noticeably more humanoid, while the males have much more prevalent fish traits. Compare Slardar◊ and Naga Siren.◊ However, Slark, a bipedal fish-creature is also described as Slithereen- it's thought by some that Slithereen is an alliance rather than a race.
• Dragons in Dragon Age have drastic differences between their sexes. Male dragons, called drakes, will only grow to about the size of a moose and never grow wings, instead travelling along the ground in search of a female dragon to mate with. Female dragons are initially around the same size at maturity albeit with wings, but once they find an appropriate nesting site and settle in they begin to grow into high dragons, the enormous flying engines of destruction feared in legend.
• Dragon Ball Online and Dragon Ball Xenoverse has the Majin race, which was introduced in the former. They were born when the good Majin Buu read one of Mr. Satan's pornographic books, decided that he wanted companionship, and created a wife; after a while they had children, which resulted in the proliferation of an entire race of beings like them. Male Majins take after Mr. Buu, having fat bodies and silly faces, while females take after Miss Buu, resembling human women but lacking noses and having head tentacles usually shaped like hair. The differences are justified as Majin Buu set the template when he patterned Miss Buu off one of the models in the magazine.
• Merpeople in Dragon Quest XI: Mermaids follow the standard pattern of human woman above the waist, fish below the waist. Mermen are fish-faced bipeds.
• In the MMORPG Dream of Mirror Online, the females of the Shura race are basically foxgirls, while the males are massive walls of muscle with short, thick, hairless tails, and one small horn in the center of their foreheads.
• Carnavin from Eden's Last Sunrise are a pretty regular, mammal-like Beast Men species, except the skeletal structure of their faces varies significantly, with males having longer and narrower canine snouts, and females having shorter and rounder feline ones. At first glance, they look like they could be separate Cat Folk and Fox Folk species.
• Mother Deathclaws in Fallout: New Vegas look noticeably different from their male counterparts, having blue skin, a broader neck, swept back horns, and a more erect stature. However, in Fallout and 2, they were identical to the males (though this can be explained away as being due to the limited graphics of those games).
• The Au Ra introduced in Final Fantasy XIV's first expansion, Heavensward, are a race of Draconic Humanoids and a somewhat downplayed example of this (But still noted as being unusual due to lack of significant dimorphism among the other playable races). The males reach heights of over seven feet tall, have very sharp features, scales all over their body, gigantic horns where their ears should be, longer tails and very aggressive body language. By contrast, the females barely reach five feet tall, have slender, dainty builds and soft faces with a difference in the number and placement of scale patches, smoother horns that curve back away from their head, shorter tails, and a much softer body language.
  • The Roegadyn are a less pronounced version, but still stand out against other races. While the males and females of other races have rather similar builds (minus obvious breasts on Hyuran, Elezen, and Miqo'tean females), Roegadyn males are clearly about three times as heavy as the females. Females have a mild Amazon build, but males are still about twice as wide, with arms thicker and more muscular than a female's leg.
• Those huge, blind, nigh-invulnerable Berserkers in Gears of War? That's a female Locust Drone. Male Drones are human-sized, and even the giant Dumb Muscle Boomers and the Large and in Charge General RAAM are dwarfed by the Berserkers. True to their name, they are constantly in an Unstoppable Rage that makes them mow down anything in their path: humans, architecture, and even other Locust, so they are usually kept chained up until released into the battlefield. Keeping them chained up is also the only way male Locust can successfully mate with them and reproduce. Oddly enough, their Hive Queen looks very human, but unreleased backstory (confirmed by Word Of God) reveals that she was a human, who was experimented on, so she could get into contact with the Locust. And we can clearly see how well that went, considering that she's the Queen.
• Granblue Fantasy: Downplayed with the vaguely bovine-themed Draphs - males and females have the same horns, Pointy Ears and great physical strength, but drastically different builds. While male Draph are slabs of muscle who tower over every other race in the game (averaging around 220cm tall), female Draphs are the second-shortest (averaging at only 130cm) and also have huge chests (ranging from G all the way to L-cup). Deconstructed in that, because Draph architecture is designed for people of wildly varying sizes, it's accommodating to a wide range of races as well, which has lead the Draph to gain a reputation as a welcoming people.
• In Grandia, the women of Laine are just humans with pointy ears, but the men are anthropomorphic bulls (and double as Nonstandard Character Design with their chubby bodies and very round, cartoonish-looking faces with no nose and Black Bead Eyes). Making things stranger, only the adult men look like this — boys who haven't come of age also look like humans with pointy ears, and apparently undergo the transformation into bulls very quickly as soon as their horns grow in, with the appearance of one boy that the party meets completely changing in the short time that it takes to go inside a house and talk to an NPC.
• Guild Wars 2: Male Norn are hulking brutes with shoulders that would put World of Warcraft to shame, while females look like tall humans.
• League of Legends:
  • Yordle females look like tiny women with blueish-purple skin and long, pointed furry ears — quite squat and with rather wide faces (depending on the artist) but basically humanoid. Yordle males on the other hand vary from looking like short gnome-like fellows with massive facial hair (but not blue skin) to resembling bipedal hamsters — either way they look nothing like the females. Compare Tristana with Teemo. This largely stems from them originally being two separate races (Yordles and Meglings) who were retconned into one. However, as time progresses the League art team is making an effort to make female yordles more outwardly furry, including giving Tristana and Lulu obvious fur texutre in Wild Rift shorts.
  • This◊ is Alistar, a male Runeterran minotaur. While he's an exceptionally-large member of his species, for comparison and scale here◊ is the Minotaur Reckoner, a more conventional male minotaur. Finally, this is Lady Aelana, a female minotaur- and here she is beside other humans for scale, showing that female minotaurs are still considerably taller than the average human (although there particularly large men can still be taller) but absolutely petite compared to their males.
• Lineage 2 has male dwarves looking like old bearded men, albeit quite short (they are dwarves after all), while females are quintessential loli girls.
• Though less extreme than some other examples, the insectoid Kephera of Lusternia straddle this trope. The males are about four to five feet tall, dexterous, hardy, and generally warriors; the females are six to seven feet tall, considerably more intelligent and charismatic, and much slower/bulkier due to their thoraxes. Their society is matriarchal, with one Queen having many mates.
• Some of the creatures in Monster Hunter are actually the males and females of the same species, despite being fairly different (or in some cases, wildly different):
  • Monster Hunter (2004): Downplayed with Rathian and Rathalos. Their designs and abilities are similar enough, but the Rathian is usually green while the Rathalos is red (they also come in pink and blue or gold and silver), and they have different elemental weaknesses (Rathian is more vulnerable to Thunder attacks, while Rathalos is more vulnerable to Dragon attacks). They also have very different tactics: Rathians prefer to fight low to the ground at close range with fire blasts and a venomous tail, while the Rathalos tends to keep airborne and attack with its fire breath and venomous talons.
  • Monster Hunter 2 (dos): Teostra and Lunastra downplay this as well. Like the Raths, their designs are similar to one another but they're dimorphic enough to warrant their own classifications (Teostra is red and has smaller horns while Lunastra is blue and has larger horns). They also have different weaknesses (Water for Teostra, Dragon for Lunastra) and different tactics (Teostra can apply Blastblight, Lunastra creates firey hazard areas).
  • Monster Hunter 4: The Seltas is a monster that resembles an enormous rhinoceros beetle. The Seltas Queen is much larger, flightless, and more resembles a scorpion with its squat body and pincered tail.
• The Dungeons & Dragons tie-in MMORPG game Neverwinter has male Fomorians be the expected hunched, deformed, warty ugly giant-kin, while the female Fomorians are basically hot amazon women with just one deformed eye.
• NOBY NOBY BOY: BOY and GIRL exaggerate one of nature's more common variants: BOY is small, while GIRL dwarfs him in size. But whereas BOY comes up to the average human's legs, GIRL is as big as Earth itself and is capable of stretching around the solar system and back.
• Odin Sphere:
  • The mini-boss Vulcans and Onyx all appear to be of the same race, but while normal Vulcans grow horns, have their hair replaced by fire and become naked when they transform, Onyx changes into something somewhat akin to a Balrog.
  • Female fairies have colorful butterfly wings, while males have (possibly vestigial) wasp or housefly wings.
• In Phantasy Star Online, the android race known as Casts display this trait when playing the Ranger class. Male Ranger Androids, RAcasts, resemble human-sized typical mecha designs with bulky bodies and stylized mechanical faces — if they can even be called faces. The female variant, RAcaseals, look like cute robot girls with slim proportions as default. The male and female Hunter Androids though, HUcasts and HUcaseals, avert this however, with both looking very humanoid in design. Future games in the series give many more options to make completely humanoid android characters of both male and female variety, as well as less humanoid females, though there is still an imbalance in which there are more mecha-style male options than there are female, and the default models used for promotional materials and when starting character creation still follow the same male/female styles as PSO's.
• Pokémon:
  • There are a number of species that are gender-exclusive (Jynx, for example, is only female). But some of these Pokémon are considered the opposite sex of a different "species." Notably (and most obviously) Nidorino and Nidorina^note The Nidoran lines' status as this is actually The Artifact, as they were introduced before the formal introduction of sexes in the games, but it would have been too much of a hassle to renumber the National Dex to accommodate them but also Volbeat and Illumise.
  • Burmy, based on a bagworm, evolves into a Mothim if male or a Wormadam if female. Their appearances are VERY different, as Mothim is a moth and Wormadam is still a pupa. (Like real bagworms.) Wormadam actually has three appearances, but that's unrelated.
  • Other examples: In the anime, a Latias produced a Latios egg like the Volbeat/Illumise thing. Some species also have sexual trimorphism: Only male Kirlia can evolve into Gallade, but both genders can evolve into Gardevoir. Only female Snorunt can evolve into Froslass, but both can evolve into Glalie. Combee and Salandit can be both genders, but only females evolve into Vespiquen and Salazzle respectively, males do not evolve.
  • Also some species have ACTUAL sexual dimorphism, as in visual differences in the same species based on gender, starting in the fourth generation games. Most of them are tiny differences (such as female Rattata having shorter whiskers or female Weavile having smaller ears) but a few species are very different. Hippopotas/Hippowdon are quite different in color. Male Unfezant have more colorful plumage than the brown-and-gray females, and a trailing red crest. Male Frillish are blue, females are pink... and when they evolve the male Jellicent gets a huge Pringles mustache while the female gets a fluffy collar. And then there's Meowstic, which takes it up another notch- the offense-oriented females and support-oriented males not only have different enough fur patterns to be two separate species, they also have different Hidden Abilities and learn different move sets. Another example is Pyroar, where the male sports a huge mane, while the female has a long, flowing mohawk. In some cases it's even applied retroactively to such classics as Pikachu: starting with Gen IV, there's a notch in the end of a female Pikachu's tail.
  • A particularly extreme example occurs with Solgaleo and Lunala. Although technically classified as genderless as with most legendary Pokémon, the two forms have extreme dimorphism of the same species. The former resembles a giant lion, the latter a giant bat. The Pokédex entries for them also point out that Solgaleo is the male of the species while Lunala is the female.
• In Ratchet & Clank, it's eventually established that Angela Cross is a Lombax, and it's implied that her lack of a tail is due to the fact that she's a female. She's also taller than Ratchet, but it isn't clear if it's this or if Angela's just unusually tall for a Lombax (or if Ratchet's just really short). However, a female Lombax, Rivet, appears in Ratchet & Clank: Rift Apart, complicating the issue. Then again, she's established as being from an Alternate Universe, so perhaps Lombaxes evolved differently in her universe.
• Rhythm Heaven:
  • The Rap Men in Rhythm Tengoku are depicted as Amazing Technicolor Population-style humanoids. Their Distaff Counterparts, the Rap Women, are instead stark-white with the colors going to their hair.
  • The Güiro lizards from Rhythm Heaven's Love Lizards. The male is small, green, and has a tail that can make maraca-like sounds, while the female is large, yellow, and can make washboard sounds by scratching her back with her tail.
• The only hard rule for designing animals with two or more sexes in The Sapling is that they all need to have the same basic torso shape. Literally everything else about them from their size, to their diet, to their behavior, and even how many limbs they have can be wildly different.
• In Shadowverse, Goblins look exactly as you'd expect of them. Female goblins, though, are more humanoid: Goblin Mage, and Goblin Princess.
• Shantae and the Seven Sirens: Wetmen compared to Wetgals: Cyclops with an eye that has a pupil, and the teeth come out from their eye to Cute Monster Girl with two green Monochromatic Eyes and an Impossible Hourglass Figure.
• The Shin Megami Tensei games have both Succubi and Incubi as recruitable demons. Succubi (and the related Lilim) resemble attractive women in skimpy clothes with wings; Incubi are small, hideous imps with a large growth (even longer than their bodies!) coming from their crotch.
• Played with in Splatoon. Regular Octarians look like anthropomorphic octopus tentacles, and it's vague whether they even have biological sexes in the first place. However, Octolings, who are Octarians capable of Voluntary Shapeshifting between an octopus form and a humanoid form, are all female in the single-player campaigns. In contrast, both male and female Inklings can change between squid and humanoid form, and exhibit only human-like degrees of sexual dimorphism. However, this trope is ultimately averted; one Sunken Scroll implies that their leader DJ Octavio is actually a male Octoling stuck in octopus form, the DJs for in-universe bands SashiMori and Diss-Pair are both male Octolings, and starting with Splatoon 2's "Octo Expansion", you can play as a male Octoling yourself (and fight alongside/against other ones in the multiplayer). The official explanation for why enemy Octolings remain all-female is because you're fighting specific elite units that only recruit females for whatever reason.
• Done uniquely in Startopia. Every single alien race you see has the same model for males and females (notable only in each individual's info, if at all). The Dahanese Sirens (referred to in everything but their intro as just "Sirens") are the only distinctly male and female species, simply looking like humans with wings. However, what we see as humanoid male and humanoid female are, actually, just the reverse according to the employee management screen.
• In Star Trek Online female Deferi have a large purple bony plate on the front of their faces, and eyes with circular pupils. Male Deferi have no plate and vertical slit pupils.
• Every species in Sword of the Stars, except the Humans and the Liir (who are hermaphroditic), have some kind of this or another. The Hivers are Bee People so this is to be expected (not to mention that workers and warriors are sexless to begin with); Zuul females are approximately three times the size of the males and animalistic while the males are weedy psionic masterminds with a specialty in Mind Rape; Tarka males that become fertile (which only about one in a thousand do, and which can only be accomplished by eating unfertilized Tarka eggs) approximately double in size; and Morrigi females are basically dragons while the males are more akin to birds. This also receives a kind of reverse-lampshading in the fluff, where it's noted that due to the death of sexism in Human society and the lack of dimorphism between men and women, most other races actually have a hard time telling the difference, which can be quite comical. The Hivers are the exception — they can detect airborne estrogen, so they can instantly pick out the females. Unfortunately for female Human spacers, Hiver battle strategy targets the females first.
• World of Warcraft:
  • Naga are some of the most dimorphic creatures in the game. The men are standard Snake People with a reptilian head, while the woman are four-armed Gorgeous Gorgons with either fins or snakes for hair. Though to be fair, this was not the result of natural evolution, but a deal Queen Azshara made with N'Zoth to save her people from drowning. Azshara came from a heavily matriarchal society and was literally named "The Vainglorious", so it makes sense she'd want the woman to remain beautiful and privileged.
  • Male trolls are very tall, permanently hunched, and have prominent tusks, while female trolls are essentially Cute Monster Girls. The difference is quite extreme, to the point that male trolls unhunched are the tallest playable race while the females aren't much taller than humans. Word of God confirmed that the hunched appearance of most male trolls is not genetic, but social: they bend over so as not to seem threatening to the females. It's also worth noting that early alpha builds had non-dimorphic female trolls, which suffice to say weren't exactly popular, but at least Blizzard tried. The Zandalari trolls are less obviously dimorphic — their men are much closer in height and don't hunch. They still have larger tusks, but that's true to life for many animals.
  • Draenei, and by extension the eredar, are the most dimorphic playable race. Aside from a significant amount of Sexy Dimorphism, males have bony crests on their foreheads and a Weird Beard of tentacles, while females instead have large curved horns, and sometimes (Depending on the Artist) small tentacles behind their ears and a very small forehead ridge. There's no in-universe explanation, but the meta reason is to give a stereotypical Hot as Hell look for eredar to fulfill and draenei to subvert.
• The Draken in WildStar have females who look mostly humanoid, compared to the hunched over and far more bestial males.
• ZanZarah: The Hidden Portal: All male goblins seen in the game are thin and lanky. All female goblins have curvier bodies, and their skin is darker and looks scaly.

• At The Heart Of It All, written by the creator of Concession featured a cute female alien who was discussing another alien race with Immy, the protagonist: "Their females look much like us, but their males are giant room-sized beasts with twelve tentacles who only think with the most primal urges of eating and reproduction..." Cut to Immy zooming off in a rocket.
• Thuxians from Buck Godot: Zap Gun for Hire exhibit a fairly mild form of this trope, assuming that the one male and one female seen in the comics are typical examples of their sex. Thuxians look vaguely like Xenomorphs in the Alien movies (they have a similarly shaped head, no visible eyes and somewhat similar tail). Al (male) is green, the back of his head is rounded and his face is shaped so that he looks to have a large nose (he doesn't seem to have nostrils, though). Tal (female) is blue and her head looks more like that of the Xenomorphs, extending further back and not having a nose like Al has.
• Dan and Mab's Furry Adventures: There is a race called the Tatanni where the females are long necked and horned humanoids while the males are six-eyed worm things that attach to a female's back, similar to the relationship female and male angler fish have^note though evidently less extreme, considering the males evidently retain their brains and intelligence. How they reproduce isn't explained because when one of them offers to explain it, the characters decline.
• "The People" in Digger are a race of bipedal, sapient Spotted Hyenas. They most certainly share the real life sexual dimorphism of Spotted Hyenas, and their culture revolves around it: the girls are Large and in Charge, but have horrific infant mortality rates. In particular, firstborn children are considered to "belong to the goddess" — like actual hyenas, the first pregnancy is almost always fatal to the child. A firstborn who survives is seen as an omen and a lucky charm, a blessed person who was given back by their deity. The author, Ursula Vernon, based a huge amount of the work on the real-life characteristics of the anthropomorphized animals; while the mythology is taken from real world myths and legends. Definitely someone who did the research, and did it well. It helps to know that Ursula was an anthropology major in college and a post-grad student of Weird Knowledge in real life. For those who don't feel like checking The Other Wiki, that means Blood Eye's Exotic Equipment looks almost exactly like Ed's with any size-difference being negligible.
• In the now-long-defunct webcomic Evilish, mermaids have fish tails while mermen have legs with fins. This makes the former jealous because only the latter can leave the sea to venture on land.
• In Gunnerkrigg Court one character is a barn-sized Giant Enemy Crab while her mate is the size of a large-ish blue lobster. He's also capable of human speech, while she must tap out her side of conversations on a keyboard next to her pool. Between themselves they speak telepathically.
• Manala Next Door posits that the all-male tengu of Japan and the all-female harpies of Greece are the same species, who just happen to be such loners that even married couples live continents apart and only meet once in a while to breed.
• In The Mansion of E, male Motihauls have tentacle-like growths on their heads, while the females look more like furless cats.
• Outsider: Downplayed. The Loroi are, aside from looking like elves with blue skin tones and odd hair colors, very similiar in appearance to humans, and thus male and female Loroi don't look drastically different from each other (aside from the obvious). However, female Loroi average at around 170cm (5'7") in height while male Loroi are much shorter. A tall Loroi male rarely gets over five feet, with most being far below that, although apparently they're more even size-wise with human men in... other areas. Because of this size difference, as well as only making up about 10% of the population, Loroi men are viewed as a weaker sex in need of protection by the females.
• Lampshaded in Sluggy Freelance, in the Years of Yarncraft MMO arc.
• TENACITY: Female Kyan, a subspecies of human, have long antennae and fox-like ears. Male Kyan have horns and pointier human ears.
• The Dugong Whale from Tower of God, where the males look like cute dolphin-seals◊ and the female... well... looks like◊ this◊.

• In Lore Sjoberg's Book of Ratings entry for "Hostess Products", it is suggested that the cake and frosting portions of a Hostess cupcake are an example of this.
• Bosun's Journal:
  • Female changeling sphinxes are four times the size of the males, and have only a small covering of hair on their heads. Males instead have a thick covering of woolly fur over their heads, necks, bellies, and backs, and only one lives in each pride. When hunting their primary prey, the sheep-like woolly humies, the male sneaks into the herd and pretends to be a lamb, in order to scout out weak or injured individuals and lead potential prey into ambushes or weaken them with a poisonous bite, after which the larger and more numerous females take it down.
  • Riddlesphinxes, the changeling sphinxes' sapient descendants, develop a more extreme form of this by exaggerating their ancestors' size differences. Male riddlesphinxes, while still sapient, are noticeably less intelligent than the females due to having much smaller brains. After becoming a mated pair, the male stays permanently on the female's back, providing fine manipulation while the female provides the thinking power and muscle. A married woman's traditional clothing includes a tent-like structure on her lower back and tail in which her husband rides in.
• This picture of a massive whale-like alien creature followed by tiny specks. A zoom in reveals that these specks are insectoid creatures and the males of the species (the description states that they are the size of a seagull).
• Mortasheen has the Q-Lex, which has a small parasitic male hanging onto the large, predatory female. This is based on actual mosquito sexual dimorphism, which is appropriate, given that this creature is a human/mosquito hybrid.
• Serina:
  • The polymorph birds are a species of softbill bird that have different morphs of male similar to the Side-blotched lizard, each with their own distinct appearances and behaviors.
    • The Ardor is only slightly larger than the female and is a monogamous breeder who will assist his mate in rearing their offspring.
    • The Keeper is twice the size of the female, are very aggressively territorial and keep harems of females.
    • The Tramp is very similar to the female in size and appearance and will use this to sneak into the territories of Keepers in order to mate with his harem before taking off.
    • The rarest morph is the Bachelor, they are nearly as large as the Keeper and much less aggressive but their most unusual trait is that they form mostly homosexual pair bonds with either other Bachelors or Ardors and will either steal or adopt the eggs of other Polymorph Birds to raise as their own.
  • The metamorph birds, a lineage that through a long series of events developed an insect-life life history with distinct larvae and adults, produce some linages with extreme dimorphism. A notable example is the strikeworm, native to the sky islands of the late hothouse age, which is noted to be the most sexually dimorphic animal of its time. The female is a blind, sessile, almost limbless animal resembling a real-life sand-striker worm, with her forelimbs modified to serve as highly venomous mandibles; she's an ambush predator that permanently glues herself within cracks in the islands' cliffsides and preys on passing flyers, and can live for many years. The male is a small, mothlike bird, feeds on nectar, and spends its few months of live searching for a female so that it can mate, take the eggs, deposit them in a colony of regular birds so that the larvae can feed on abundant carrion, and then die of exhaustion.
• Orion's Arm has, in general, six genders, approximately defined as male, female, hermaphrodite, female pseudohermaphrodite, male pseudohermaphrodite, and genderless. Due to the advanced technology in the setting, it's trivial for someone to switch from one gender to another.
  • One clade has four genders, three passing on a different type of tissue (plant/animal/technological), and one acting as a womb.
  • The Singers are aliens who are 'born' in groups of one female and several males that live together. The females are sophont, the males are not. To mate, a male of one group stings the female of another group (their venom doubles as sperm), while a female's sting can cause another female to fission.
  • The Daharrans are an alien species with three genders, consisting of males, females and non-reproductive individuals that handle nest-tending and child-rearing. Interestingly, it is the neuter gender which plays the dominant roles in Daharran society, being both larger and more intelligent than the sexed castes.
• Hamster's Paradise:
  • The early Temporcene tetracorns (ox and deer-like herbivores descended from hamsters) of South Easaterra have become highly dimorphic with males growing significantly larger than females while also developing vibrant color patterns and elaborate horns as a way of attracting mates.
    • One species in the middle Temperocene, the fourform fourhorn, does something unusual with this. The normal state of the species is that of a larger, more colorful male pairing off with a small drab female during the mating season with the male using his greater size to protect his mate and young from rivals and predators alike. However, several million years earlier, a mutation in their chromosomes resulted in the usual dynamic being flipped around, with large brown females and small yellow males. Rather than split into distinct species, they will usually form pairs that consist of a standard male and a large female since the offspring of such pairings usually have a higher survival rate while the smaller ones make do with each other and form larger herds to compensate. Since these couplings typically have a roughly 50/50 number of normal to mutant calves, this means that the species effectively has four sexes.
  • The apex predators of North Westerna is a pterodent known as the pterowrist. The males are condor-like flyers that specialize in small animals and carrion while the females are over five times their size and are flightless cursorial hunters similar to terror birds that target large animals though both sexes are very similar at birth. It's explained that that this developed so that they don't compete over the same food sources and came about due to the larger female pterodents becoming even bigger when they made it to the island.
    • This gets taken further by one of their descendants, the pterowrex. The females are large megafaunal hunters that can weight up to 700 kilograms and can kill elephant sized prey while the males are stork-like flyers that typically feed on small rodents. This also means that they have a unique dynamic with the female's primary prey, the maustodon, who will fight against the females trying to eat them but have no problems with the males perching on them to either feed on the small animals fleeing their footsteps or even picking through the maustodon's fur to eat parasites, ignorant of the fact that they're the same animal.
  • The wingles are lizard-like rodent descendants that fly using modified scales, the females are both significantly larger than the males but are also much more brightly colored, unlike many real-life species which have large but drab females and small but colorful males. The reason for this is because it's only the males who care for the offspring so they require better camouflage while females only contribute their genes so they become vibrant as a way of attracting a mate.

• The Amazing World of Gumball:
  • Tobias is short and squat, with hair covering his face. However, his sister Rachel is taller and more humanoid. This also extends to their parents, with Harold being covered in hair and their mother being more humanoid.
  • Jamie has a tail, a button nose, and a cylindrical yellow cap/hair with bull horns poking out. Her dad has no tail, no nose, and a cap/hair shaped like an upside-down golf tee with triangular horns sticking out.
• Ben 10 introduces a race of aliens known as Sludgepuppies. Both genders in their species looks like dark-purple blob creatures, but the females in particular sport long catfish-like whiskers and larger eyes, whereas the males' eyes are smaller, and they don't possess any distinct features.
• Butt-Ugly Martians: The sole female Martian is named Shaboom Shaboom. The male Martians are all bug-eyed and have skeletal faces, while Shaboom Shaboom is prettier and is noticeably a bit more humanoid in face and body shape.
• Chowder: Both the titular character, Chowder, and his "love interest" Panini, are said by Word of God to be the same species of bear, cat, rabbit... thingies. Despite this, the former is grey and bares no obvious rabbit features, while the latter is pink and has prominent "bunny ears" that can cause some to mistake her as just a rabbit at first glance. Though they do have similar cat-like tails and sharp teeth and the final episode shows they both have large, bear-like builds as adults.
• The Fairly OddParents!: The Boudacians (Princess Mandie's species). The females look like human women with yellow skin, purple hair, and antenna; the males look like werewolves.
• Monster Buster Club: The show has possibly the most truly extreme example with Grampa Smith and Cathy. Grampa Smith, in his true form, looks like a sort of blue-skinned fish-fly thing with four limbs. Cathy's true form, on the other hand, has six tentacle-like limbs, white skin with pink spots, three crests on her head, and a squirrel-like tail. However, since Cathy’s parents are never shown, it is unknown if they are biologically related or if they are related through adoption. If they are biological related, one possible Fanon explanation is that along with all of their other Combo Platter Powers, their species possibly has extreme environmental adaptation at birth that they lose when they reach their child or teen years and thus stuck with whatever form they got, with Grampa Smith possibly being raised in an aquatic environment while his granddaughter was not. Another possible explanation is that their species has a version of puberty for adults or elderly that makes them look like Grampa Smith from their original form like Cathy.
• Redakai: Zane and Zair are a minor example. Despite being siblings (therefore most likely the same species), Zane has green skin, blue hair, and darkened eyelids — while his sister Zair has light red skin, dark red hair, catlike eyes, and a strangely familiar patch of bumps on her forehead.
• Rick and Morty: The Gazorpians genders are so completely different that one would be forgiven for thinking that they are two different species, with the males being hulking ogre-like beasts with reddish skin and the females resembling tall humanoid women with telekinetic abilities. In fact, the only physical feature that they share is their three pairs of arms, with one pair being on their heads in place of ears. They are shown to look identical as babies, with the females losing their red skin as they age.
• South Park: A throwaway gag has a male Gelgamek, a stocky green individual marginally larger than a male human of similar age and social standing, mention that the Gelgamek vagina is three feet wide, and filled with razor-sharp teeth. One can only imagine what the rest of the Gelgamek female looks like.
• Star Wars: The Clone Wars:
  • Dathomirians are a hybrid between Zabrak (Darth Maul's species) and humans. While the males hardly look any different from full-blooded Zabrak, females lack horns and thus look similar to humans.
  • The Terrelian Jango Jumper females have human-shaped hands and feet. Star Wars Rebels reveals that males have symmetrical four-fingered hands (two fingers, two thumbs) and tridactyl feet.
• Superman: The Animated Series: Behold Mr. Mxyzptlk and his girlfriend, Gsptlsnz◊. They're both 5th-dimensional imps with godlike powers, though, so it's possible that they both just choose to look that way.
• Tom And Jerry: The series, (as well as other Golden Era cartoon short series for that matter), had male cats and mice which still look like, well, cats and mice except they're standing on two legs. This is in contrast to the female characters such as Tootles who look much more anthropomorphic. A particularly glaring instance of this can be seen in the short "Muscle Beach Tom", where the girl cat that Tom (and Jerry) is flirting with more or less looks like a human female with a cat's head. (She doesn't even have a tail!)
• Wakfu:
  • While Sadida are both similarly human below the neck with strategically placed Garden Garment, all males have their entire head covered in green hair, while the females only have green hair on top of their head that falls past their shoulders like human women.
  • A Downplayed Trope with Sram as they both can appear as attractive men and women in skeletal motif tights, some males can also appear as full-blown skeletons with no skin or organs.
• Wander over Yonder: A Downplayed Trope with Zbornaks (Sylvia's species). In the episode “Family Reunion”, Sylvia returns to her home planet with it being revealed that females and male a few minor differences, with the latter being larger with rhino-like horns on their snouts and a few spines on their tails.

• In general, in most species where males and females are of disparate sizes, the female is often the bigger one, as she has to produce larger eggs as opposed to the microscopic sperm of the males. The exceptions are when males physically fight over females, with natural selection favoring bigger males: examples include cichlids, horned beetles, and many species of mammals including some apes.
• Fish:
  • In some species of anglerfish, after the male attaches himself to the female, his body degenerates until only his testes remain. He ceases to exist as an independent organism, and the female has sperm on tap for the rest of her life. No surprise why the angler fish won the titles of The Most Extreme in the episodes "Oddities" and "Appendages". There's a song about it. And a small comic on it, too.
  • Whalefish and bignoses are members^note female and male, respectively of the same species of abyssal fish so wildly different from one another that for the longest time, scientists thought that they were entirely different One-Gender Race species. Not only that, but they have a juvenile stage which is completely distinct from both of them and was itself mistaken for a third species.
  • In several fish species, males come in two varieties: conspicuous, muscular macho-males who use aggression to monopolize access to females, and small, inconspicuous ones that resemble females so they can sneak into harems and fertilize eggs without the macho-males noticing them.
• Molluscs:
  • Female Blanket octopus Tremoctopus violaceus can be 100 times bigger than males, and 40.000 heavier. While females may reach 2 m (6.6 feet) in length, the males are 2-2.4 cm.
• Birds:
  • A great many birds have brightly-colored males and plain, often larger females. In fact, the word for a male hawk or falcon is "tiercel", which comes from the French word for "one third", because male raptors are a third smaller than females. This makes a certain evolutionary sense — the female has to carry eggs, so a larger body is needed. Males can get away with being smaller (and thus needing less food) because birds generally don't physically fight except in extreme circumstances — it's too easy to hurt a wing and be crippled. Similarly, males normally are bright and females drab so that a nesting female is hard to spot but a displaying male easy to find. (There is also a theory that some species, like peafowl, are essentially advertising their fitness as a mate by showing off a major handicap — a big tail says "Hey, I can walk around with this strapped to my butt and still avoid predators! I'm an awesome provider!" Zoologists are rather stumped by the peacock — despite what the obvious human assumption would imply about displaying it, actual observance of peahen's mating preferences don't seem to be consistent with anything about the tail — one tail seems, as far as zoologists can tell, as good as another.) The purpose of the size difference in male and female birds of prey is also to discourage competition for food between a mating pair. The larger female can catch large prey (and have plenty to feed her chicks) without worrying about the small male getting in her way.
  • Peafowl are good examples of extreme difference between the sexes, as are most Galliforms (chickens, pheasants, turkeys, etc.).
  • For an inversion of the usual trend, see the Eclectus Parrot. Males are a well-camouflaged (but bright) green, females are a gaudy red, blue, and purple (Eclectuses are one of the only parrots to practice polygamy, and the females' bright colors make it easier for the male to find his ladies on their respective nests). They were actually classified as two different species until (it is rumored) someone caught them mating.
    • This was especially unexpected given that unlike most orders of birds, parrot species tend to be so un-dimorphic that it's hard to tell the males and females apart for sure without a blood test or a scope up the cloaca.
  • Another odd inversion are the phalaropes. For some reason, this group of little Arctic shorebirds have reversed the usual avian gender roles. Females are brightly colored and fight over males, who are drabber and stay with the nest. They have been described elsewhere as "an entire genus of Wholesome Crossdressers".
  • Ostriches split the difference: both males and females spend time brooding the eggs, but because females do so in the daytime and males brood at night, the males have black feathers and the females have dusty-brown ones. Thus, each sex camouflages the nest during its babysitting shift.
  • The huia, a strange bird native to New Zealand which was driven extinct by overhunting, had an entirely unique form of sexual dimorphism. The male and female had the same feather markings, but their beaks were shaped very differently. They had separate niches and ate in different ways: claims that they had to work as a team to eat are based on a misunderstanding.
  • An equally dramatic form of sexual dimorphism, if not as distinctive as that of the huia, was found in another group of NZ birds—Dinornis. This genus included the largest specimens of the flightless moa, which were hunted into extinction around 1400 by the Māori. Females of the largest species within Dinornis were up to twice as tall and three times as heavy as males of the same species (up to 12 ft/3.65 m, 500 lb/227 kg).
• Snakes:
  • Female pythons and boas are larger than males, for similar reasons to birds of prey.
  • In all python and boa species, both sexes have small claws, known as spurs, on either side of the cloaca. However, they are larger in males, who use them to "tickle" females during courtship.
  • European adders are a rare colour example, with the males being silver grey with a black zigzag down their backs, while females are light brown with a brown zigzag. Occasionally, both sexes feature a melanistic black variation.
• Males of the common side-blotched lizard are famous for demonstrating genetic polymorphism. In their case the males come in three different variations, or "morphs," that operate on Tactical Rock–Paper–Scissors. Each has different color blotches, they vary in size, and they all utilize different mating strategies.
  • Orange-throats really get around, using their larger size and greater aggression to gather big harems.
  • Blue-throats are monogamous, and prone to having their mates stolen by oranges. They, however, work cooperatively with fellow blues, warning each other of intruders and even altruistically fighting off rival oranges to give their neighbor blues a chance to mate.
  • Yellow-throats look enough like females that they can sneak into the orange-throats' harems and reproduce with them on the sly. But they can't pull this trick off with blue-throats, who have an easier time protecting their single mate and work together with other blues.
  • You might have noticed this puts them in sort of a rock-paper-scissors set-up: Oranges steal Blue mates, Yellows cuckold Oranges, and Blues catch Yellows. This means that all three varieties can all live in the same territories, as there's always someone they can outcompete. As all three types are able to reproduce to equal success, the three are at an evolutionary stalemate, with neither strategy being the most "fit" to pass on their genes.
  • But wait, there's more! It turns out that the females come in orange and yellow too! Orange-throated females lay many small eggs and are very territorial. Yellow-throated females lay fewer, larger eggs, and are more tolerant of each other. This makes for even more possible combinations.
• Southern Sea Lions. The females are small and sleek, much like what most people recognize as a seal. Males, on the other hand, are thrice as big, and surprisingly look a lot like actual lions, with squared-off snouts with large powerful teeth and shaggy manes around their necks not unlike their feline namesake.
• Spotted hyenas are a case of Bizarre Sexual Monomorphism: females are larger than the males and have almost identical-looking genitals to males, with a "pseudopenis" (enlarged clitoris) and "pseudotestes" (fatty lumps in a scrotum-like sac). They mate, urinate and give birth through the clitoris, and it tears apart during the first birth. Sometimes the hyena's first cub dies during birth because of suffocating within this structure. It is theorized that this is a result of increased production of testosterone — creating stronger and more aggressive females who are more capable of fighting and surviving in the literal dog-eat-dog world of the savannah, although why only this species of hyena exhibits this characteristic is still a mystery.
  • Hyena genitals are so hard to distinguish that quite infamously, one zoo in Japan unsuccessfully tried to breed a pair of hyenas for several years...only to find out later that both hyenas were actually males.
• The duck-billed platypus is bizarre enough as it is, but to top it off, male platypuses are actually venomous, delivering an agonizing cocktail of toxins through a horny spur on their hind legs. Female platypuses lack venom glands entirely, and their spurs are smaller and are often shed in infancy.
• The male musk deer, a tiny antlerless cervid, is distinguished by a pair of SABER TEETH. Yes, a saber-toothed deer. The same can also be said for the Chinese water deer. This identifies both species as having separated from their cousins a very long time ago - all cervids had tusks until the development of antlers.
• Very common among arthropods:
  • An important distinction between insect sexes is that only female ants, bees, or wasps are in fact capable of stinging: their stingers are modified from ovipositors, an egg-laying organ. Males, being short-lived drones that exist solely to mate with the queen and dies a few days later, have no use for such defenses.^note Plus they don't have an analogous structure to modify into a stinger
  • Spiders are infamous for examples of extreme dimorphism between the sexes. There is a tendency of the males to evolve into wanderers, spending their lives looking for more sedentary, web-bound females, resulting in them evolving to very different lifestyle requirements.
    • Male salticids (jumping spiders) are often brightly colored and have very large "boxing glove" pedipalps in front, while females are brown or gray with small palps (P. audax, a common lab spider, is an exception to the color rule). Probably because salticid females are very aggressive hunters, some species' males do elaborate (and hilarious) dances to increase the probability that females will recognize them as a mate rather than a snack.
    • We all know how different female spiders have a tendency to eat the male for one reason or another, but in some species the male actually tries to get eaten! In these cases, he will, after starting the process of sperm transfer (which is typically done with a pair of legs next to his face), rotate his abdomen up toward the female's head and dangle it appetizingly. This is advantageous for the male, because it will provide her with valuable nutrition when she's finishing up the eggs he's fertilizing and putting them in their egg case. Given the longevity of these male spiders, and the travel time to the next female, he's extremely unlikely to ever encounter a second female anyway.
    • Bolas spiders have not only very different appearances, but predation methods. Female bolas spiders are relatively large, and instead of spinning webs, they hang a single sticky silk thread, then swing them at approaching moths to ensnare them, hence the name. Male bolas spiders, on the other hand, are 7 to 10 times smaller than the females, are colored differently, and while they also don't spin webs, they forgo the silk entirely and just grab prey with their front legs.
  • Scale insects are even more extreme than the spiders in terms of body-dimorphism. As juveniles, males and females look much alike, but when the females mature, they sink their mouths into a plant and become something that looks less like an animal than a wart. Mature males develop wings and fly around looking for females (for a few days, before they die).
  • Even more so than the scale insects, barnacles of the genus Sacculina are... unusual. Males are free-living, wandering animals that don't resemble typical barnacles at all. Females resemble neither barnacles nor the males. As adults, the females parasitize female crabs and look like a generic mass of cancerous tissue rather than a separate animal at all. The adult males also discard their crustacean exoskeleton and implant themselves into the females, becoming basically a packet of sperm. here's a site to read more about ''Sacculina''...
  • Fig wasps. Males are tiny compared to females and wingless. They also have short stumpy legs with which they clumsily waddle about inside the fig fruit. Once mated, he cuts open a hole in the fig for the winged female to escape and dies, never seeing the light of day outside the fruit. Additionally, mating is always between siblings!
  • Bagworm moths. The females are wingless, eyeless, near-legless breeding machines. These were fictionalized as the Pokémon Burmy, as seen on the page image. The male moth mates with the female while she is still in the cocoon, and in some species, particularly the asexually-reproducing ones, the young hatch out of the female Alien style.
  • Eusocial insects have sexual trimorphism: the reproducing females look different than the Worker females, which look different from the males. And some ants have sexual TETRAmorphism: reproducing males, reproducing females, workers, and soldiers.
  • The adult females of some species of firefly are virtually indistinguishable from the larvae (i.e., grubs), while only the males are the elongated beetles we all know and love. This is actually not uncommon among insects, and they're known as larviform females. Aside from fireflies, they also occur in some moths, midges, and twist-winged insects; one of the most extreme cases occurs in the trilobite beetle, where the female can be a few inches long and resembles a spiny trilobite, but the male is less than one centimetre and looks like a normal beetle.
  • Siafu/driver ants. The females are not small for ant standards (being about an inch long). The male is about the size of a large sausage, hence the term "sausage fly" for him. The "sausage" part is a bloated abdomen that makes them look like very obese dragonflies. This abdomen? Contains sperm. When they breed the females release a pheromone that attracts the male, who usually have nothing to do with the females (for good reason!). The females chew off all his limbs and carry him with them until the queen is ready to mate. Then they rip open his belly so the queen can impregnate herself with the contents while the other females eat him.
  • Tarantula hawk wasps (the wasps that capture tarantulas as hosts for their eggs) do this on purpose. The female has the ability to choose the gender of her eggs; fertilized eggs produce females, while unfertilized eggs produce males. If she captures a female tarantula, which tends to be huge, she will lay a female egg on it. If she captures a male or juvenile tarantula, which tends to be small, she will lay a male egg on it. With less meat to feed on, the male wasp grows up to be smaller than the female.
  • Paracerceis sculpta is a marine isopod that lives in sponges. The Alpha morphs is large, aggressive, and defends a harem of females. The Beta morphs resembles the females, even mimicking their courtship behavior, and sneaks into harems to mate beneath the Alpha's nose. The Gamma is instead really tiny, enough to hide in holes on the sponge, and comes out to mate when the Alpha is distracted.
• Inverted by various functional hermaphroditic species, in which "male" and "female" exist in the same individual at once. Played with by a few species that change sex according to age; which "sex" is young and which is old usually depends on which would be more advantaged by large size.
• Unlike most worms, nematode roundworms have separate males and females, and live parasitically in the gut of humans and other mammals. As is the case of many species, the female is bigger, but the male is distinguished by a distinctively coiled and curly tail! Inverted with the whipworm Trichuris trichiura, where the male is bigger and bulkier. While the thick portion of the female's body is slightly curved and shaped like a banana, the male's coils around 360 degrees and resembles a spiral.
• The blood fluke Schistosoma is known as the "romantic parasite", because its very different male and female are often obtained in specimens clasped together in a loving wormy embrace (ew). The male is very thick and fat, and has a long narrow groove down his body where the thin and slender female inserts herself into. As the male feeds on the blood of the host, the female gets to share some too, being provided food, shelter, and a ready available mate all in one when she is finally ready to lay her eggs.
• While male and female mosquitoes look alike, the bizarre sexual dimorphism here is not physical appearance but diet. While the male mosquito is a harmless vegetarian that feeds on flower nectar and plant matter, the female thrives on blood- the vampiric, plague-bearing pest dreaded by all (she actually drinks nectar too, but prefers blood when given the choice). This is because female mosquitoes need the protein and iron in blood for their eggs.
• Primates:
  • Humans' sexual dimorphism isn't as great as that of our near relatives (men are usually about 5" taller and 45lbs heavier than their sisters). Gorilla and orangutan males are enormous compared to the females (in addition, mature male orangutans develop cheek flanges and throat pouches), while male and female gibbons sport different colors of fur, plus an inflatable throat pouch for males of some species. It's even more extreme in the larger monkeys, such as baboons, mandrills, or proboscis monkeys.
    • Mandrills in particular show the most sexual dimorphism of any other monkey. Male mandrills are the largest monkey species in the world, while a female mandrill is only about half his size. In addition, male mandrills' faces are much more colorful than female mandrills'. This image compares a female and a male mandrill side-by-side.
  • Boobs! Er, to elaborate, human females are about the only creatures with naturally permanently swollen breasts, and they don't even need to become pregnant for them to get like that (pregnancy just swells them more). Other mammalian females have rather flat teats until they get pregnant. (Though some human women don't grow much in this area, either. Art also shows that what was average before the Industrial Revolution would be pretty small today.)
    • One theory is that this is due to the relatively flat faces humans have compared to other primates — our lips don't protrude nearly as much, so without those inflated breasts to suckle on, babies would mash their noses against tougher tissue, making it harder to breathe. The "aquatic ape" theory has things to say about buoyancy during breastfeeding instead. Yet another relates it to the upright walk humans perform — primates generally have a thing for shapely butts and when walking on all fours, these tend to be permanently on display. When humans started walking upright, they looked for a substitute and naturally swollen breasts worked perfectly. But whatever it really is, the actual reason remains a mystery.
    • The word manatee comes from a Caribbean word for breast. The extinct giant manatee is reputed to have had breasts.
  • Also, human male penises are gigantic compared to other primates (yes, even your Teeny Weenie is massive compared to a gorilla's; "hung like a gorilla" is not a compliment), leading some to believe that before the advent of clothing they, like human breasts now, served as a sexual display in addition to their other functions.
    • Another thing is that humans don't have a baculum (penis bone), as one of the only two species of primate (including other apes; they are sporadically present among mammalian species) without. Erection is supported only by blood pressure so, in conjunction with the already over-average size, it means that sexual performance is directly connected to good health (both physical and mental). Which just makes "boner" an ironic name.
    • We and gorillas both have a gestation period of about 8.5-9 months. A healthy human newborn will weigh roughly twice what a healthy newborn gorilla will. A newborn human's brain is also almost as large as what an adult gorilla has and a human baby will be helpless for far longer. Because of this; human female reproductive organs have to be larger, which could also affect male organs.
    • The human beard is thought to have originally operated on logic similar to the above peacock and his "I'm obviously badass to have survived so long with this thing attached to me" tail, only instead of making you easier for predators to catch, a beard made you easier to beat in a fistfight, since your opponent grabbing you by the beard puts you in almost as compromised a position as putting you in a headlock. Meanwhile, human females usually have far shorter, thinner beards than females of other great ape species.
  • The recently discovered fossil of an adult male Australopithecus afarensis revealed him to have been five to five-and-a-half feet tall. Compared to his female conspecific Lucy, at three-and-a-half feet, this is quite a substantial size difference between sexes, even if it's assumed he was tall and Lucy was short for their species.^note As very few fossils of Australopithecus have been discovered, it's impossible to know whether these examples are typical, or if they were on the extreme high and and low ends of the species' size range.
    • When their heights are scaled up to match those of modern humans the relative height difference between the two isn't all that different than the height difference between an NBA Center (who are very large men) and a female Olympic Level Artistic Gymnast (who are very small women). If that height difference was normal for them, it would mean that Australopithecus afarensis males were three to four times more massive than Australopithecus afarensis females.
  • Because humans practice body modification — at least to a far greater extent than any other species — this is most commonly used to vastly exaggerate these factors (though it depends a great deal on the relevant culture for, say, Long Hair Is Feminine). In some cases, this has led to a cultural expectation for this trope to apply when it actually doesn't. For example, in Western culture in the 21st century hair in the armpit is regarded as something men should have and women shouldn't, despite the fact that most women naturally do. Sure, men are usually hairier, but a woman who's healthy and fertile is unlikely to have none.
    • Some of these body modifications can also result in some forms of artificial sexual dimorphism, based largely on those same cultural expectations. In a few examples, the Kayan people of Burma have women who wear stacked brass coils that appear to greatly elongate their necks (it is also said that these also provide protection against the bites of tigers (and, we assume, vampires). In China, the notorious practice of foot binding meant that a good proportion of Chinese women had feet shaped differently than the males. This can even include things such as earrings and tattoos. Traditionally, earrings were seen as something only women wore and a woman with tattoos was seen as unseemly. While these may no longer apply in modern Western cultural standards, there are still some exceptions (for example, men don't normally wear earrings in both ears or large earrings like the giant hoop variety, and a woman with a fully tattooed arm is generally seen as unusual or noteworthy).
• Elephant seals, whose males are about 3-4 times bigger than the females, and have a proboscis-like snout (hence the name). In addition to this, females are mature enough to breed at an age of 3-4 where as males are of breeding age at 5-6 years, but won't have that giant nose until 8 years old. Because of this, there are two breeding behaviors between the older and younger males (Alpha Breeders and Beta Breeders). Alphas will attract a large harem of females, ranging form 30-100 individuals. Betas generally are not successful in attracting a mate, but they do try, often acting as a guard of an Alpha's harem and chasing other males away in exchange for a chance to mate with a female while the Alpha is busy. When that fails, an Betas still look a lot like females and will use this to get close enough to mount an unsuspecting female.
• Male lions' manes, deers' antlers, narwhals' tusks, and many (though not all) male bovids' horns (particularly among antelope) set them apart from females of their species, although in the deers' case, their antlers drop off at a certain time of year.
  • Narwhals are a particularly odd example, as males' tusks serve as sensors for sensing movement of prey in the water, as well as temperature and as clubs for stunning fish. Female narwhals, however, lack the tusk, but don't seem to be handicapped in hunting in any way. To make things even more unusual, a small percentage of female narwals indeed do grow tusks, and neither males nor the rare tusked females ever use them as weapons against other narwhals (the tusk is far too fragile and sensitive for that) so the reason why the tusk is sexually selected for males is still unclear.
  • The caribou is the sole deer species in which both sexes have antlers, though the females' are smaller. The males' are shed after the autumn rut, whilst the females retain theirs through the winter — it's thought this helps them compete for food with the larger males during this harsh season. This also means that all Santa's reindeer are females! (Not really implausible, as most of them, except Rudolph, have feminine or gender-neutral names anyway...)
• Male rotifers (a type of freshwater zooplankton) are barely a quarter the size of females, and are so single-mindedly dedicated to mating that they don't even have mouths. The males starve to death after only a day or two, whereas the females (which eat algae) last a week or more after hatching. To make it even more extreme, a certain class of rotifers, the Bdelloidea, completely abolished all males. It is an entire class with around 450 described species (it is hard to count because there are no shared genetic pools, so we have to rely on morphological differences), reproducing exclusively through parthenogenesis.
• Like spiders, some species of octopus have much larger females. An extreme example is the argonaut, where the female is about five times larger than the male, and secretes a calcareous egg case that looks like a nautilus shell, using a pair of highly-modified tentacles. Female blanket octopi are about 2 meters long, while males are a few centimeters. Also, in the case of these octopi, they used to find some strange parasitic worm inside the females. Turned out it was the males' Exotic Equipment.
• Well-known pterosaur Pteranodon is known to have differed so much between sexes that, like the creatures above, the males and females were mistaken for different species initially. The male Pteranodon was much larger (an 18-foot wingspan was the average and some findings suggest that even larger wingspans were possible) and had an enormous crest on top of his head. The female was smaller (12-foot wingspan) and had a tiny or even non-existent crest.
• Tetrahymena thermophila is a protozoan with seven sexes or genders. Coupling can occur between any two of the microscopic critters, but only unlike pairings can reproduce.