The Cameraman (Buster Keaton, 1928)
The gags are great, and as usual Keaton's film contains glorious comic spectacle showcasing his incredible athleticism (The Tong War scene among other scenes in this case), but what makes Buster Keaton such a unique comic talent is his distinctly dead pan face he always manages to maintain despite his hapless antics. Behind the surface level humor lurks a subtle commentary on the newsreel cameraman's profession. My favorite scene is the juxtaposition of Keaton shooting a gunfight with his camera next to a monkey shooting a machine gun. Later the monkey actually works the camera as well.