William Mervine (14 March 1791 – 15 September 1868) was a Rear Admiral in the United States Navy, whose career included service in the War of 1812, the Mexican–American War and the American Civil War.
Born in Philadelphia, Pennsylvania, Mervine was appointed midshipman in January 1809. Serving on Lake Ontario during the War of 1812, he later cruised off Africa and South America, in the West Indies and in the Pacific.
While in command of the Savannah during the war with Mexico, 1846–47, he led a detachment of sailors and United States Marines against Monterey, California, and on 7 July 1846, took possession and hoisted the American flag over the city. On 7–9 October 1846, Mervine led 203 U.S. Marines, 147 American sailors, and volunteers in the invasion of Los Angeles where he lost the Battle of Dominguez Rancho. Fourteen Marines were killed. José Antonio Carrillo, a Californio rancher, led 50 Spanish Californio lancers in that defeat of Mervine and the American forces.
The Navy has named two destroyers USS Mervine in his honor.