Admiral of the Fleet Sir Thomas Byam Martin, GCB (25 July 1773 – 25 October 1854) was a Royal Navy officer. As captain of fifth-rate HMS Fisgard he took part in a duel with the French ship Immortalité and captured her at the Battle of Tory Island during the French Revolutionary Wars. Then while in command of the third-rate HMS Implacable in the Baltic Sea and attached to the Swedish Navy he took part in the capture the Russian ship Sewolod (Vsevolod) during the Napoleonic Wars.
During his many years of service as Comptroller of the Navy, Martin was credited with reducing the fleet from the enormous size deployed against the French to a much more streamlined service geared toward protecting merchant trade and the British Empire. He also focused heavily on employing highly trained dockyard staff capable of responding rapidly to any international emergency. Martin also sat in Parliament for 14 years and was an outspoken critic of government attempts to reduce the Navy budget which ultimately saw him dismissed in 1831 by his old friend King William IV.
Martin died in October 1854, at the early stages of the Crimean War, planning the Baltic Campaign and investigating the possibilities of using poison gas weapons.
Martin was promoted to captain on 5 November 1793 and given command of the fifth-rate HMS Modeste, a frigate recently captured from the French, and saw action in operations off Toulon at an early stage of the French Revolutionary Wars. He went on to command the fifth-rate HMS Artois and saw action at the siege of Bastia in April 1794. Martin was then transferred to the Channel Fleet and stationed off Ireland in HMS Santa Margarita, in which he captured the French frigate Tamise at the Atlantic raid of June 1796: in the engagement, Tamise was badly damaged and suffered heavy casualties while HMS Santa Margarita's losses were only two killed and three wounded.