HMS Trafalgar is a decommissioned Trafalgar-class submarine of the Royal Navy. Unlike the rest of the Trafalgar-class boats that followed, she was not launched with a pump-jet propulsion system, but with a conventional 7-bladed propeller. Trafalgar was the fifth vessel of the Royal Navy to bear the name, after the 1805 Battle of Trafalgar.

After Operation Veritas, the attack on Al-Qaeda and Taliban forces following the September 11 attacks in the United States, Trafalgar entered Plymouth Sound flying the Jolly Roger on 1 March 2002. She was welcomed back by Admiral Sir Alan West, Commander-in-Chief of the fleet and it emerged she was the first Royal Navy submarine to launch Tomahawk cruise missiles against Afghanistan.

Trafalgar was decommissioned on 4 December 2009 at Devonport.