Ever since my mind was corrupted by Monty Python I can never see John Cleese benig in even a semi-serious role.
Geoffrey Rush has grown on me. I mean this guy (a long with Johnny Depp) really brought up the performance of Curse of the Black Pearl...and was a sorely missed asset in the 2nd movie. He added so much depth to the 'evil' character of Barbossa that you just don't get to see in a lot of typical bad guys. We see Barbossa's plain out conniving and 'mutinous' side, but also his longing for wanting to get rid of the curse (the apple scene with Keira Knightly was fantastic), and plus his slightly light-hearted comedic side. He wasn't your stereo-typical bad guy and added several dimensions to his character in POTC that you just don't see.
Also, he had a small role in Munich, yet was a good influence in the movie. I haven't seen
Quills or
Les Miserables, but I've heard these are buy far some of his best movies.
I don't know who he'd be, as he's not really a leading type guy, but good in a support role (or villain). I can perhaps see Beorn being a good fit, or providing the voices for the trolls.