USS S-15 (SS-120) was a second-group (S-3 or "Government") S-class submarine of the United States Navy. Her keel was laid down on 13 December 1917 by the Lake Torpedo Boat Company in Bridgeport, Connecticut. She was launched on 8 March 1920 sponsored by Mrs. Simon Lake, and commissioned on 15 January 1921 with Lieutenant Commander David R. Lee in command.