HMS Magnificent was a 74-gun third-rate built for the Royal Navy in the first decade of the 19th century. Completed in 1806, she played a minor role in the Napoleonic Wars.
Magnificent measured on the gundeck and on the keel. She had a beam of , a depth of hold of and had a tonnage of 1,732 <small></small> tons burthen. The ship's draught was forward and aft at light load; fully loaded, her draught would be significantly deeper. The Repulse-class ships were armed with 74 muzzle-loading, smoothbore guns that consisted of twenty-eight 32-pounder guns on her lower gundeck and twenty-eight 18-pounder guns on her upper gundeck. Their forecastle mounted a pair of 18-pounder guns and two 32-pounder carronades. On their quarterdeck they carried two 18-pounders and a dozen 32-pounder carronades. Above the quarterdeck was their poop deck with half-a-dozen 18-pounder carronades. Their crew numbered 590 officers and ratings. The ships were fitted with three masts and ship-rigged.
Magnificent was the second ship of her name to serve in the Royal Navy. She was ordered on 24 January 1805 from Perry, Wells & Green as part of the second batch of five Repulse-class ships of the line designed by Sir William Rule, co-Surveyor of the Navy. The ship was laid down at their shipyard in Blackwall Yard in April and was launched on 30 August 1806. She was commissioned by Captain George Eyre in September and completed at Woolwich Dockyard by 24 October.
On 21 March 1810, she participated in the expedition against the island of St Maura in the Adriatic.
From June to August 1812, she was off the coast of Northern Spain, in support of operations to expel Bonapartist forces from Spain. From 30 July to 1 August, she launched an attack on Santander.
She was among a convoy of vessels that had departed from Cork and Portsmouth in September, which arrived at Jamaica on 12 November 1814. With the departure of Vice Admiral Cochrane on 29 November 1814, she was the most senior vessel in Jamaica, her commanding officer Willoughby Lake was deputised to carry on the duties of Senior officer on the Jamaica station. She was among a convoy of vessels that had departed the West Indies on 1 May 1815, having paused at Havana, then stopped at Castletownbere on 3 July, arrived at Deal on 10 July 1815. She was paid off on 8 August 1815.
She was hulked in 1825, and eventually sold out of the service in 1843.