Kovin was an Entharan trader who dealt in weapons. He was capable of designing and making modifications to numerous weapons technologies in his lab at the Entharan colony planet in the Delta Quadrant.
In 2374, Seven of Nine accused him of violating her in order to steal her nanoprobes. She noted that Kovin stunned her and used equipment in his lab to extract nanoprobes in her system. He denied the charges, and agreed to allow Tuvok to conduct an investigation. At first the investigation revealed that there were nanoprobes present in the lab.
Fearing that he would be arrested unjustly, he fled in his ship. Tuvok and The Doctor would discover that Kovin was innocent; when he fired a weapon to demonstrate it to Kathryn Janeway, it activated Seven's nanoprobes, causing Seven to create a false memory about her assimilation. When Janeway hailed Kovin to tell him that they believed that he was innocent, he didn't believe them, and fired on USS Voyager. This caused an overload in his weapons which caused an explosion that destroyed his ship, killing him. (VOY: "Retrospect")
Kovin was played by actor Michael Horton and his stunt double Chester E. Tripp III. Horton filmed his scenes on all days of production for this episode, between Tuesday 11 November 1997 and Wednesday 19 November 1997, on Paramount Stage 8, 9, and 16. His costume was later sold off on the It's A Wrap! sale and auction on eBay. [1](X)
Kovin was named by Bryan Fuller. He named the character after a friend of his, Johnny Kovin. Since Fuller had "always thought it was such a cool name", he used it for this Star Trek character. (Information from Larry Nemecek)