Tom Waits has been cast as the devil in Terry Gilliam's The Imaginarium Of Doctor Parnassus, also known as Heath Ledger's final film. He was careful to point out that he's not 'a devil,' but, rather, 'THE devil' in the movie. He also confesses that he's not sure why Gilliam chose him for the role.
Perhaps it's because Tom Waits personifies the devil better than any other human being on the planet, but that's just a stab in the dark. The movie gets more interesting as news trickles out, but, being a Terry Gilliam film, we're not sure it will ever see the light of day.