USS Lillian II (SP-38) was an armed motorboat that served in the United States Navy as a patrol vessel in 1917.

History
United States
Name	USS Lillian II
Namesake	Previous name retained
Builder	Willard Downes, Bayshore, New York
Completed	1909
Acquired	Chartered 6 June 1917 Enrolled in Coast Defense Reserve 8 June 1917 Taken over 16 June 1917
Commissioned	20 July 1917
Decommissioned	19 December 1917
Fate	Returned to owner 20 December 1917
Notes	Operated as private motorboat Lillian II 1911-1917 and from December 1917
General characteristics
Type	Patrol vessel
Tonnage	13 tons
Length	50 ft (15 m)
Beam	10 ft (3.0 m)
Draft	3 ft (0.91 m)
Speed	10 knots
Complement	4
Armament	1 × .30-caliber (7.62-millimeter) machine gun

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.

Assigned to the 3rd Naval District at New York City, Lillian II operated as a shore patrol boat in Great South Bay on the southern coast of Long Island, New York.

The Navy decommissioned Lillian II on 19 December 1917 and returned her to her owner on 20 December 1917.