Rear-Admiral John Hayes CB (1767 or 1775 – 7 April 1838) was a prominent British Royal Navy officer of the late eighteenth and early nineteenth centuries. Hayes was best known for his skill at seamanship and his interest in the design and construction of naval vessels, beginning with his childhood education at Deptford Dockyard where his uncle Adam was a master shipbuilder. During his naval service he participated in the first and the last significant frigate actions of the French Revolutionary and Napoleonic Wars, from the inconclusive engagement between Embuscade and HMS Boston in 1793 and the capture of USS President in 1815. After the war's end, Hayes was appointed as superintendent of HMNB Devonport and later was commander in chief off West Africa.
In 1787, Hayes was sent to the ship of the line HMS Orion under Sir Hyde Parker. In 1790 he moved to the frigate HMS Pearl under Captain George Courtenay and followed Courtenay to HMS Boston in 1793 after the outbreak of the French Revolutionary Wars. Within months, Boston was engaged in action with the French frigate Embuscade at the action of 31 July 1793. Embuscade had been anchored in New York City harbour, and Courtenay sent an offer of battle in to Captain Jean-Baptiste-François Bompart, who sailed out to meet him. In the ensuing engagement, Courtenay was killed and Boston badly damaged. The ship was eventually forced to flee before Embuscade, escaping into the Atlantic.
Despite the inconclusive end to the engagement, Hayes was promoted on his return to Britain and joined HMS Dido under Captain Sir Charles Hamilton, moving with Hamilton to St Fiorenzo in the Mediterranean shortly afterwards. In 1799, while serving in the West Indies, Hayes was promoted to commander and in 1802 became a post captain. For the next seven years he remained in reserve, before taking command of the ship of the line HMS Alfred in 1809, assisting in the evacuation of troops from Galicia, Spain following the Battle of Corunna. Later in the year he served in the Walcheren Expedition in HMS Achille and then moved to HMS Freija in the West Indies in December 1809, almost immediately participating in the action of 18 December 1809 and the invasion of Guadeloupe.
In 1812, Hayes moved to command HMS Magnificent off Brest, and in her gained fame for keeping his ship steady during a gale while anchored in the Basque Roads. The wind was so fierce that Magnificent lost both anchors and was almost driven onto rocks. Only an extremely skillful act of seamanship from Hayes saved Magnificent and her crew from the rocks, and Hayes was afterwards known as the "Magnificent Hayes". In response to a string of British defeats by powerful American frigates at the start of the War of 1812, Hayes suggested that several old ships of the line be razeed to create 56-gun ships. The idea was accepted and Hayes given command of one of the razees, HMS Majestic. Although the razees did not meet any American frigates directly, Majestic did encounter the Terpsichore at the action of 2 February 1814, and defeated her in a lengthy engagement, the French ship sinking soon afterwards. The following year, Hayes was present at the capture of USS President, but Majestic was not closely engaged.