HMS Gannet is a Royal Navy Doterel-class screw sloop-of-war launched on 31 August 1878. It became a training ship in the Thames in 1903, and was then loaned as a training ship for boys in the Hamble from 1913. It was restored in 1987 and is now part of the UK's National Historic Fleet.

The Doterel class was a Royal Navy class of screw-driven sloops. They were of composite construction, with wooden hulls over an iron frame. They were a revised version of an 1874 design by the Royal Navy's Chief Constructor, William Henry White, the Osprey-class sloop. Two of the class were lost, one to an explosion off Chile and one wrecked off Canada. Gannet is preserved at Chatham Historic Dockyard.