HMS Royal Sovereign was a 100-gun first-rate ship of the line of the Royal Navy, which served as the flagship of Admiral Collingwood at the Battle of Trafalgar. She was the third of seven Royal Navy ships to bear the name. She was launched at Plymouth Dockyard on 11 September 1786, at a cost of £67,458, and was the only ship built to her design. Because of the high number of Northumbrians on board the crew were known as the Tars of the Tyne.