HMS Trenchant (P331) was a British T class submarine of the Second World War built at Chatham Dockyard.

Trenchant under her captain Commander Arthur Hezlet, DSO, DSC acted in the Far East mostly off South East Asia against Japanese shipping sinking a range of vessels both transports and warships, using her torpedoes, gun and also by ramming.

On 27 October 1944, "Chariots" carried into action by Trenchant sank a Japanese Army cargo ship, the Sumatra Maru in Phuket harbour, Siam.

Her most significant action during the war was on 8 June 1945, when she sank the Japanese cruiser Ashigara at a range of 4,000 yards with five out of eight torpedoes fired.

The action in the Bangka Straits earned her commander a second DSO and the US Legion of Merit, and the ship the battle honour "Malaya 1944-45".