USS L-9 (SS-49) was an L-class submarine of the United States Navy. Her keel was laid down on 2 November 1914 by Fore River Shipbuilding Company in Quincy, Massachusetts. She was launched on 27 October 1915 sponsored by Miss Heather Pattison Baxter, and commissioned on 4 August 1916 with Lieutenant (junior grade) P. T. Wright in command.