The Parthian-class submarine or P class was a class of six submarines built for the Royal Navy in the late 1920s. They were designed as long-range patrol submarines for the Far East. These boats were almost identical to the Odin class, the only difference being a different bow shape.

HMS Pandora was a British Parthian-class submarine commissioned in 1930 and lost in 1942 during the Second World War. This class was the first to be fitted with Mark VIII torpedoes. On 4 July 1940 she torpedoed and sank the French aviso Rigault de Genouilly off the Algerian coast. In an extension of the Lend-Lease program, Pandora, along with three other British and French submarines, was overhauled at Portsmouth Naval Shipyard in the United States. She was sunk on 1 April 1942 by Junkers Ju 87 aircraft from Sturzkampfgeschwader 3 at the Valletta dockyard, Malta.