Buster Keaton, 1924. The film-projectionist who walks into the screen. 45 minutes of perfect physical comedy.
From Wikipedia
Sherlock Jr. is a 1924 American silent comedy film starring and directed by Buster Keaton and written by Clyde Bruckman, Jean Havez, and Joseph A. Mitchell. It features Kathryn McGuire, Joe Keaton, and Ward Crane.