USS Allen (DD-66) was a Sampson-class destroyer of the United States Navy launched in 1916. She was the second Navy ship named for Lieutenant William Henry Allen (1784–1813), a naval officer during the War of 1812. She was the longest-serving destroyer on the Naval Vessel Register when she was sold in 1946 and was one of the few ships in the US Navy during World War II which was completed during World War I.