1. Vincent Price - The Story of Mankind (1957)
This is a strange one. Vincent Price stars as the Devil in a movie pitting Satan against an angel in a legal battle before the council of elders from outer space. The verdict will decide if humanity lives or dies. The court case takes us through human history trying to determine if mankind is essentially good or essentially evil. Along the way we see Joan of Arc (Hedy Lamarr), Sir Isaac Newton (Harpo Marx, of all people), Cleopatra, Queen Elizabeth I, Hippocrates, Nero (Peter Lorre), Marie Antoinette, Hitler, Caesar, Shakespeare, Moses, Helen of Troy, and Napoleon (among others). This is a must-see movie for anyone who enjoys the old films.
Weird or Wonderful? - Wonderful. Almost everything Vincent Price did on screen was wonderful. That's my list of 20 favorite Devils. There are about 880 more appearances of Satan in films. I'm sure you have a few favorites I didn't cover. Let's hear it in the comments.