3. Jaqen H'ghar
The Boba Fett of Game of Thrones – if Boba Fett ever, y'know, actually did something. Played with sleepy-eyed sex appeal by Tom Wlaschiha, Jaqen's a curiously courteous prisoner who slowly reveals himself to Arya Stark as quite possibly the most dangerous man in Westeros. You want to know more about him, but worry about what you might find out (with good reason, as we discovered in the finale).