in no specific order:
Star Wars: Original Trilogy [episodes IV, V, and VI]. (they're effectively one big movie)
Star Trek II, III, and IV. (same reason, also... "KHAAAN!!")
The Incredibles. the only movie I have literally been forced to watch thousands of times (not by family children either) and can still enjoy... that is one hell of a feat.
The American President. Shut up, I liked it. It launched The West Wing, and is one of maybe 4 non-Tom Hanks "chick movies" I can stand to watch. (yes, Tom Hanks is that good)
Mel Brooks. I tried to pick just one Mel Brooks movie to make the list and I just can't. Its like choosing the angriest pro wrestler (...'s character), just can't be done. So I'll list the great ones: History of the World, Part 1; Spaceballs; Robin Hood, Men in Tights; Blazing Saddles; ...can't think of any more, but they're all great, and hilarious.
Runners-Up: Batman (1989), Batman (1966), Spider-Man, X-Men, Leslie Nielson (specifically the Naked Gun movies), Pixar (the rest of their work. especially Toy Story and Up), 101 Dalmations (and most of the Disney classics), The Dark Knight, Superman, Idiocracy, Tom Hanks (I love Tom Hanks, he made some fantastic movies, but none of them are as dear to me as Mel Brooks's work. sorry, Tom), A Few Good Men (and pretty much everything with Jack Nicholsen), Monty Python and the Quest for the Holy Grail, The Simpsons Movie.