The Professor X figure of the original Exiles in the Ultraverse comic books. Useful if you need a well-meaning scientific genius type.
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.