This is who I came in to mention. I saw a post by someone here once who said they could swear Weaving wore a dozen masks with different expressions in this movie, so good was he at conveying emotion with only his voice, bearing and gestures.
An amusingly captioned sample containing a couple of wonderful scenes can be found here.*
*(Contains minor spoilers - action takes place shortly after the movie begins.)
Not doing an accent but just Pete Serafinowics brilliant diatribe in Shaun of the Dead(He was the sensible house mate)just before he goes Zombie plus his long suffering plea earlier in the film including the immortal "That was funny once,about ten years ago…for about twenty minutes…(Not verbatim)
For accents though Miranda Richardson(Queenie in Blackadder2),amongst others she does the spoiled grown up little girl,the suave British upper middle class and the hard bitten Ulster Woman in the crying game.
Oh I forgot Telly Savalas plays to a T the Wise cracking, no nonesense wheeler and dealer from Brooklyn in er… every single thing he ever appeared in,including no doubt Hamlet and The Life of Wagner.
I never thought anybody would surprise me like Bob Hoskins did; I didn’t find out he was British until many years after I’d seen Roger Rabbit. But Carla Jean?? Wow. I never saw that coming. I’ve seen Alfred Molina play a British character (the lead in a play called Howard Katz) and I didn’t know/forgot he was British.
Any time I heard John Lithgow and especially Jason Alexander sing, my mouth falls open. Neither of their speaking voices gives a clue to their marvelous tenor abilities.
I can’t believe no one’s mentioned Andy Serkis’ tour de force as Gollum.