12 Angry Men is a hard one to top, a great movie that has been consistently kind of a let down when they try to remake it.

Beyond 12 Angry Men though, can't believe no one has even brought up Ben Hur or the 10 Commandments. Oh man, the original Strangers on a Train was in the 50s too. Lots of movies too that may not hold up in modern times but made entire genres or concepts viable. Notable shout out for Harvey and North by Northwest.