The XCom Project in 2012 video games XCom: Enemy Unknown and XCom: Enemy Within has essentially no background. So here is a complete, and completely made-up, one with a full history and explanations about how stuff works and why.
Writeups.org is an encyclopaedia of characters in genre fiction — comic books, video games, action movies, etc. It offers illustrated, researched profiles. These also include technical data for role-players. If you need a robust understanding of a character’s abilities, personality, history, etc. this is *the* place to be.