[Thesinner]

V - Hugo Weaving - V for Vendetta
Commodus - Joaquin Phoenix - Gladiator
Merlin - The Sword and the Stone (dunno the voice actor's name)
Ron Burgundy - Will Ferrell - Anchorman
Capt. Jack Sparrow - Pirates Trilogy - Johnny Depp
Steve Stifler - Sean William Scott - American Pie
Seth - George Cloney - From Dusk Til Dawn
William Wallace - Mel Gibson - Braveheart
Mr. Blonde - Michael Madsen - Reservoir Dogs
Matt Damon and Edward Norton - Rounders
Brad Pitt and Eric Bana - Troy
Boromir - Sean Bean - Lord of the Rings
Evey Hammond - Rachel Weiss - The Mummy
Ms. Vaughn - Bridgette Wilson - Billy Madison
Kiera Knightley in anything...

Can't think of much else.