Thomas Greer Carless (1806 - December 16, 1848) was a British hydrographer and naval officer active in the Indian Navy. Carless distinguished himself in the First Anglo-Burmese War (1824-1826). Following the war, he was assigned to assist Robert Moresby in the important 1831 – 1833 survey of the Red Sea, for which he is today best known. Carless was next assigned to Captain Haines where he produced a hydrographic survey of the South Coast of Arabia. In 1837, he was transferred to Africa in the vicinity of Cape Guardafui (Ras Asir, Somalia) where he surveyed much of the coast. In 1838, Carless was sent to survey the Indus River, work for which he is less well known but which is perhaps his most historically significant. This included the first survey of Karachi Harbor, presaging the 1839 British East India Company occupation of subsequent development of that city as a major port. Carless' work with Moresby in the Red Sea was highly praised for by none other than Richard F. Burton, who wrote in First Footsteps in East Africa,

The beautiful maps of the Red Sea, drafted by the late Commodore Carless, then a lieutenant, will ever remain permanent monuments of Indian Naval Science, and the daring of its officers and men.
He was subsequently variously employed throughout the region, including 1846 survey correction work in the Persian Gulf. There he attained the rank of Commodore and was given command of the Persian Gulf Squadron, but he unfortunately contacted Small Pox shortly after and died in the city of Bushehr (Iran).