Elexis Sinclaire is a fictional character in the SiN first-person shooter video game series by Ritual Entertainment. Elexis is the main antagonist character in the cyberpunk-themed SiN series, where she is a rich and powerful mad scientist who is secretly engaged in organized crime and planning to make an radical artificial evolutionary advance to the human race, and enemy of the protagonist character, private security force commander John R. Blade. She was introduced in the game SiN in 1998.

Elexis is also the main antagonist in Sin: The Movie, an anime film produced by ADV Films along with Ritual Entertainment. In the 2006 game SiN Episodes, her design was based on the model Bianca Beauchamp. Elexis is often perceived as one of the most sexual (either sexiest or most sexualized) female characters in video gaming. As such, she received a polarized but mostly positive critical reception.