1) Darth Vader, Star Wars, movie. Truely evil if you can use the force to choke someone through a screen.
2) The Prophet of Mercy, Halo 2 and 3, video game. To me he was powerful and corrupt because he controlled an army and it's every belief, at one moment.
3) Davy Jones, Pirates of the Carribean, Movie. Gave no Mercy and laughed at the love. Amazing.
I'm such a geek at times. Lol.