The man has one of the best “Oh noes, I’m falling!” faces in movie history.
These guys just tend to steal scenes in whatever movie they happen to be in. Gary Oldman was the best reason to watch The Fifth Element, he was just such a delightfully, unapologetically over-the-top sleazy bad guy. He was just as much fun to watch in Batman Begins when he played Detective Gordon, the very straightforward, normal, honest everyman character of the movie.
And I was telling one of my supervisors at work how you can always tell if a movie is going to be entertaining if Dennis Hopper is in the cast. He is able to apply just the right amount of cheese to his roles.
In The Good, The Bad, and The Ugly, Eli Wallach stole most of the scenes as Tuco. That said, I’m still not sure if he counts for this, since of the three central characters in the movie, and the one arguably the most peripheal to the plot of the, he got more character development than Blondie and Angel Eyes combined, being the only really relatable guy in the whole movie. That said, he has one of the most awesome lines in movie history with “If you need to shoot, shoot! Don’t talk.”