HMS Saturn was a 74-gun third-rate ship of the line of the Royal Navy, launched on 22 November 1786 at Northam. The vessel served during the Napoleonic Wars with the Channel Fleet, taking part in the 1801 Battle of Copenhagen. With the beginning of the War of 1812, Saturn was modified to become a frigate designed to take on large American vessels of that type. Saturn was deployed as part of the blockading squadron of New York City from 1814 to 1815. From 1825, the vessel was in harbour service and was broken up in 1868.