Gareb was an Aenar who was forced to pilot the prototype Romulan drone ship for the Romulans in 2154.
Gareb was abducted a year prior to Enterprise NX-01's arrival at Andoria, around November 2153. Gareb was kidnapped by the Romulans from Andoria and told that he was the last Aenar. In November 2154, he piloted a Romulan drone ship via telepresence, in an effort to provoke a war between the Tellarites and the Andorians who he believed had exterminated his people. After the drone ship was heavily damaged, Gareb suffered from mental fatigue. The Romulans used stimulants on Gareb. Later, he helped the Romulans launch an attack against the Enterprise and a fleet of allied starships, using two drone ships.
Jhamel, his sister, was on board Enterprise, and was able to communicate with Gareb. She told him the truth, and he felt guilty that he was forced to destroy so many ships, and to kill so many people. Jhamel appealed to him to end the violence. He had one drone ship attack the other, destroying it and allowing the Enterprise to destroy the other one. He was executed in the process by the Romulan Valdore, but was telepathically comforted by his sister at the end. (ENT: "The Aenar")
Gareb first appeared as a background character in ENT: "Babel One", played by uncredited actor Glen Hambly, before becoming a recognized character in "United" and "The Aenar", where he was played by credited actor Scott Allen Rinker.