Because you like V in V for Vendetta
Sarah Kerrigan is pretty much the Queen Bitch of the Universe. See them in StarCraft .
A powerful mob boss, Vito Corleone is always making offers people can't refuse. See them in The Godfather.
After being resurrected and discovering his new morphing abilities, Alex Mercer uses them to combat the virus now ravaging New York. See them in Prototype Series.
If Lisbeth Salander can hurt a bastard who deserves it by digging up stuff about him, she feels good. See them in The Girl with the Dragon Tattoo.
Liu Kang spends his days training his body and spirit, seeking to become the ultimate warrior. See them in Mortal Kombat.
A few millennia in the mortal realm have caused DEATH to be quite enamored of life. See them in Discworld.
The only thing Albert Wesker cares about is turning himself into a God. See them in Resident Evil Series.
Mr. Blonde is the undisputed leader of his pack of suited-up outlaws, with a stoic and serious demeanor, and a penchant for bloodshed. See them in Reservoir Dogs.
Ava may just be the perfect woman. So long as she can pass a Turing test. See them in Ex Machina.
They say they saved Adam Jensen by turning him into a cyborg, but he's not sure saved is the right word. See them in Deus Ex Series.
Mystique is a shape-shifting mutant who, after too many disappointments, does not want to co-exist with humans. See them in X-Men Series.