Herbert Lom played Napoleon Bonaparte in Young Mr. Pitt in 1942 and again in War and Peace in 1956
Ian Holm played Napoleon in * Napoleon and Lone* (1974), Time Bandits (1981), and in the Emperor’s New Clothes (2001)
John Carradine played Dracula in House of Frankenstein (1944), House of Dracula (1945), Matinee Theater (TV, 1956), Billy the Kid vs. Dracula (1966), Nocturna (1979), and countless times on stage (as well as several almost-but-not-quite Count Dracula characters).
And Dean Norris.
Has anybody mention Jerry Haleva? He frequently portrayed Saddam Hussein.
And Jesse White (AKA the original Maytag Repairman) played the orderly Mr. Wilson in both versions.
Curiously, IMDB says that his character was Martin Wilson in the original and Duane Wilson in the TV remake.
Paul Sorvino and Joe Viterelli who had uncredited roles as the Morolto mob in The Firm basically play every character they ever play in any movie.
As did Jaimie Foxx as Django in an uncredited post-credits scene.