Okay, Mark Hamill isn't just Luke Skywalker, star of Star Wars. He's also Luke Skywalker, star of Empire Strikes Back and Return of the Jedi.
And he's done a bunch of voice acting, like the Joker in venerated program Batman: The Animated Series. He returned to the role for Batman: Arkham Asylum and will once again for the sequel Arkham Asylum 2. But after that, he's apparently done with the character.
"This will be my last, there's no question about that. But it's the last hurrah."
Smart money says he'll be back and will be voicing the character in one way or another.