2. Boris Karloff (Frankenstein 1931, Bride of Frankenstein 1935, Son of Frankenstein 1939)
3. Lon Cheney Jr. (Ghost of Frankenstein, 1942)
4. Bela Lugosi (Frankenstein Meets the Wolf Man, 1943)
Remember that scene in Tim Burton's movie Ed Wood where Bela Lugosi (played by Martin Landau) was talking crap about Karloff playing the monster? "Its all grunting and make-up..." I always laugh during that scene because Mr. Lugosi has been in several Frankenstein movies. He's played Ygor (my favorite Lugosi character, better than Dracula in my opinion), and, of course, the monster. I read somewhere that they cut all of his lines in this movie because people didn't want to hear the moster speak with a Hungarian accent.
5. Glenn Strange (House of Frankenstein 1944, House of Dracula 1945, Abbott and Costello Meet Frankenstein 1948)
6. Christopher Lee (The Curse of Frankenstein, 1957)
7. Peter Boyle (Young Frankenstein, 1974)
8. Robert De Niro (Mary Shelley's Frankenstein, 1994)