What would be a good theme song for a badass "good-guy" character?

He's a hero, but he's also a little 'dark'. He saves people but he also likes toying with bad-guys. Overall, he's unbelievably powerful, but only when he goes all out.... and that's only when he's gonna kill someone. I thought the song 'Nightmare' by Avenged Sevenfold would work ok, it's close to what I want, but not quite. Helpsies?