Yojimbo (1961)
Since this is a classic, it may have been listed here before.
Regardless, I'll still say a few things, because it's as entertaining a movie as I've seen. (Saw it previously, years ago.)
Yojimbo is the Japanese version of the American western and, in turn, led to the spaghetti westerns. It's an action adventure with basically no special effects (aside from the hand that says hello at the beginning). It gets by on superb photography, awesome (quirky) soundtrack, great lead actor, and a story that moves right along.
The story is a morality tale that includes comedy, tragedy, drama, intrigue, and more comedy. The hero is a nihilist scruffy samuri warrior who comes to town to sell his services to the highest bidder, and there happens to be a civil war going on at the time...