6. Trevor Phillips (GTA V)
Most Grand Theft Auto characters are at least a little unstable, its almost a staple of the franchise at this point. In fact, having a moralistic protagonist in a GTA game almost defeats the entire purpose of the series, but most characters demonstrate at least some restraint. CJ from San Andreas had no qualms with chasing down a trainload of gangsters armed to the teeth with machine guns, but he showed remorse for having to kill his two closest friends Ryder and Big Smoke. Admittedly, thats not much to go on, but its something. Trevor on the other hand, is the embodiment of depravity and psychosis. Not only is he a killer, torturer and implied cannibal, but he also doesnt seem to value the lives of even his closest friends. Case and point: his relationship with his friend Floyd. Not only does Trevor abuse him (pretty tame for a GTA game) and get him attacked by soldiers as a distraction during a heist (again, not too bad) but then its implied that he takes sexual advantage of Floyd (Okay, beginning to cross the line) finally murdering him and his girlfriend for asking Trevor to leave their house (aaand the line is now a dot). Trevor is a bad guy already, just swap some of his allegiances and he can play the antagonist in any future instalments of the series. You wouldnt even need to change that much about his character, or anything for that matter. Hes a pretty detestable villain already.