It just struck me that Alan Rickman would have played Denethor much better than whoever it was in the Peter Jackson movie. That idea has opened the floodgates...

So without further ado

Frodo Baggins Johnny Depp
Samwise Gamgee Christopher Biggins
Merry Eddie Izzard
Pippin Simon Pegg
Aragorn Clint Eastwood (c. 1980)
Gandalf Alec Guinness
Legolas Paul Newman
Gimli Meatloaf
Boromir Mel Gibson
Bilbo Baggins Christopher Walken
Tom Bombadil Bill Bailey
Elrond Tim Curry
Gollum Richard O'Brien
Galadriel Brigitte Nielsen
King Théoden Brian Blessed
Grima Wormtongue Rowan Atkinson
Éowyn Sigourney Weaver
Saruman Christopher Lee
Denethor Alan Rickman
Faramir Kurt Russell
Treebeard Ernest Borgnine
The Witch King of Angmar Rutger Hauer
Sauron Laurence Olivier