Which actors/characters from either series would you like to see in a superhero movie?

So I'm watching The Dark Knight as I'm typing this, and thought that Gary Oldman (Sirius Black from Prisoner of Azkaban) played an awesome Commissioner Gordon in this movie. Although he wasn't the superhero or villain, he still played his part well. If you could take either an actor or character from Harry Potter and/or Twilight you would like to see in a superhero movie, who would it be and why? They could either be the heroes or the villains if you'd like.

For me, I would love to see David Tennant (who played Barty Crouch Jr. in Goblet of Fire) as The Riddler in the next Batman movie. There were many rumors circulating that David would be perfect in the role. He's already proven he can play a villain role very well, and he looks like The Riddler in my mind. This picture proves why he would play him so well.