HMS Euryalus was a Royal Navy frigate of 36 guns, built at Bucklers Hard and launched in 1803. In 1805, captained by Henry Blackwood, she led the squadron of frigates watching Cádiz prior to the Battle of Trafalgar. The Franco-Spanish fleet left Cadiz on 20 October and the frigates shadowed them until they were met and destroyed by the main Royal Navy fleet.