10. Vaas Montenegro - Far Cry 3
Not the main antagonist of Far Cry 3, but who the hell remembers him? or her? Vaas stole the show from that unknown person - as well as the protagonist - with the actor's performance, the constant reuse of the "Insanity definition" speech.
Responsible for the deaths of the protagonist, Jason's, brother and running a slave trade behind the scenes. Vaas is constantly playing with his enemies, or attempting to kill them slowly: incineration, drowning and just any kinds of torture you can think of.
Despite having a rather underwhelming death and an undeserving one, Vaas will forever be stuck in the dark depths of our minds, evil in its own right.