USS Ensign (SP-1051) was a United States Navy patrol vessel in commission from 1917 to 1919. Ensign was built as a private motorboat of the same name in 1914. In 1917, the U.S. Navy acquired her under a free lease from her owner for use as a section patrol boat during World War I. She was commissioned on 17 September 1917 as USS Ensign (SP-1051) with Boatswain's Mate W. C. Mills, USNRF, in command. The Navy returned Ensign to her owner on 30 January 1919.