USS Lillian II (SP-38) was an armed motorboat that served in the United States Navy as a patrol vessel in 1917. Lillian II was built in 1909 by Willard Downes at Bayshore, New York, as a private motorboat of the same name. The U.S. Navy acquired Lillian II from her owner, S. F. Rothschild of Bayshore, under a bare-boat charter on 6 June 1917 for World War I service. She was enrolled in the Coast Defense Reserve on 8 June 1917, delivered to the Navy on 16 June 1917, and commissioned as USS Lillian II (SP-38) on 20 July 1917 with Ensign S. Cohen, USNRF, in command.