6. Saren (Mass Effect)
Saren was the main baddie in the first Mass Effect game. You find out that he knows about the Reapers plans for total extinction of all organics (what you know before the sequels). He was actually trying to "save" organics by pledging servitude to the Reapers in hopes that they will be spared.
Alas, he ends up being indoctrinated as time passes and he becomes blind to his own crimes. You actually have the choice to make him realize the error of his ways and he will commit suicide.