malakite

Durandal, of the Marathon series. Take a male version of Cortana from Halo, make it smarter, funnier and crazier. And give him overwhelming control of one lone Security Officer/undercover cyborg.

Absolute badass.

Oh, and an honorable mention to Ash, of Evil Dead fame. He gets onto the list on a technicality since the character is the most badass character in the world, even though the Evil Dead games have been largely disappointing.

Edit: I just noticed that almost the exact same thing was said about Ash a few posts up. Oh well. It bears repeating. Ash=ultimate badass.