Last night I played Resistance: Avalon, which includes a "Merlin" character. (Others as well, but Merlin is the centerpiece and the only one we played with.) He is town-aligned, with the special power that he knows who all the Spies/"Minions of Mordred"/scum/mafia are.
The catch is, at the end of the game, if the spies lose, they get to confer and pick out Merlin. If they are correct, they win the game.
I played as Merlin last night in a 7p game and boy, it was one of the best gaming experiences I've ever had. Being Merlin is incredibly stressful. You hold so much power, but if you overplay your hand, you can totally cost your team the game.