USS S-33 (SS-138) was a first-group (S-1 or "Holland") S-class submarine of the United States Navy. Her keel was laid down on 14 June 1918 by the Union Iron Works in San Francisco, California. She was launched on 5 December 1918 sponsored by Mrs. Thomas M. Searles, and commissioned on 18 April 1922 with Lieutenant George P. Lamont in command.