USS Ontario

USS Ontario may refer to:


 * USS Ontario (1812) was a lake schooner in the United States Navy during the War of 1812
 * USS Ontario (1813) was a 16 gun rated sloop of war in the United States Navy during the years following the War of 1812
 * A screw sloop was laid down in 1863 as Ontario, renamed New York in 1869, and sold while still on the stocks, in 1888
 * Another Ontario was launched in 1908, decommissioned 7 April 1913, converted into a repair ship and renamed Prometheus in 1914
 * USS Ontario (AT-13) was a single screw seagoing tugboat commissioned in 1912 and served until 1946