HMS Spencer was a 74-gun third-rate ship of the line of the Royal Navy, launched on 10 May 1800 at Bucklers Hard. Her designer was the French émigré shipwright Jean-Louis Barrallier. She served in two major battles, Algeciras Bay and San Domingo, and in a number of other campaigns. She was broken up in 1822.

The Algeciras campaign was an attempt by a French naval squadron from Toulon under Contre-Admiral Charles Linois to join a French and Spanish fleet at Cadiz during June and July 1801 during the French Revolutionary Wars prior to a planned operation against either Egypt or Portugal. To reach Cadiz, the French squadron had to pass the British naval base at Gibraltar, which housed the squadron tasked with blockading Cadiz. The British squadron was commanded by Rear-Admiral Sir James Saumarez. After a successful voyage between Toulon and Gibraltar, in which a number of British vessels were captured, the squadron anchored at Algeciras, a fortified port city within sight of Gibraltar across Gibraltar Bay. On 6 July 1801, Saumarez attacked the anchored squadron, in the First Battle of Algeciras. Although severe damage was inflicted on all three French ships of the line, none could be successfully captured and the British were forced to withdraw without HMS Hannibal, which had grounded and was subsequently seized by the French.