Voldemort
He-who-must-not-be-named begins as a sort of Dickensian figure — an orphan boy cast out in a world that feared and couldn't understand him. Yet he's embraced by another, secret magical one, reared up in it, and excels at mastering its mysteries. But rather than show gratitude, he grows obsessed with his own brilliance and lust for power and turns, for lack of a better phrase, toward the dark side. By the time the Harry Potter storyline actually kicks in, Voldemort is a creature twisted by hate. He's an archetypal villain, quick to kill. His minions are the unpleasant-sounding Death Eaters, all of whom are possessed by his fascistic loathing of "Mudbloods" and those not of pure wizarding stock. In all, it's not a good look, and it doesn't help that he needs to torment another little orphan boy to fulfill his plans for wizarding domination.