Dial M for Murder - Alfred Hitchcock (1954)
Very clever and loads of fun (although obviously not a comedy). Based on a play and filmed mostly in one room so I think the original writers should get most of the kudos. Grace Kelly isn't much of an actress but she is pretty to look at. The beginning is a little too fast and confusing but thankfully you can rewind to catch up. Once the ball starts rolling it's very compelling. And the ending is very satisfying although just a touch unrealistic.