I like Sylar off the Heroes' TV show because he's a throwback to the old style villain who didn't have to have some complex psychological motivation to justify his behavior. He makes no pretense or apology for what he is or does; he just is what he is.
He started as a garden-variety psychopath/collector who seemed to have no mercy and would cause as much pain as possible, just because he could. (His power is that of intuitive aptitude -- he understands how things work, and he can "learn" the powers of other superhumans, becoming an eclectic grabbag of abilities and thus quickly more powerful than other superhumans.)
He then was in a position to try and reform himself, because he wasn't happy, and momentarily struggled with his identity.
He finally decided that it was all a lie and at heart he actually was a predator.
But the interesting thing is that, in the process of deciding that, he has set practical goals for himself and no longer preys on people the way he used to. Whereas before he seemed to go out of his way to hurt others out of boredom or because he could, now he seems capable of making decisions and coordinating with others in ways that help him accomplish his higher-end objectives. At times he has tolerated the presence of others, even providing a fatherly influence/guidance to one character about life in general, rather than just settling for short-term gratification for himself.
Whereas before he was ruthless, now he's a bit more accessible on a human level even if he's still just out for himself. It's kind of an odd style character growth.