Here are a few. Sadly, several of these actors ended up making a lot of "direct to video" movies:
* Darren McGavin in MAN WITH THE GOLDEN ARM
* George C. Scott in THE HUSTLER and in ANATOMY OF A MURDER
* Jerry Lewis is THE KING OF COMEDY
* George Kennedy in COOL HAND LUKE
* John Savage in THE DEER HUNTER
* Eric Roberts in THE POPE OF GREENWICH VILLAGE and in STAR 80
* Michael J. Pollard in BONNIE AND CLYDE
What are some others?
Post Edited (03-14-04 20:42)
From the films reviewed at this site, here is my (Ahem! Cough! Cough!) laundry list of a baker's dozen of some of the best supporting performances.
American Werewolf in London: Griffin Dunne
Creepshow: Stephen King
Day of the Animals: Leslie Nielsen
Deep Rising: Kevin J. O'Connor
Dune: Sting
Flash Gordon: Max Von Sydow
The Fly: Vincent Price and Herbert Marshall
The Fog: Jamie Lee Curtis
Plan 9 from Outer Space: Tor Johnson
Planet of the Apes: Roddy McDowell
Tarantula: Leo G. Carroll
Wizards: Fritz
and how can I forget Chris Pitt as Kevin, the boy scout, in "Lair of the White Worm."
Robert Beatty (no relation to Warren) in WHERE EAGLES DARE, whoever was Jones in THE HUNT FOR RED OCTOBER.