USS Markab (AD-21) was a Hamul-class destroyer tender named for Markab, the third-brightest star in the constellation Pegasus. Built as the cargo ship Mormacpenn by Ingalls Shipbuilding Company of Pascagoula, Mississippi; launched 21 December 1940; acquired by the United States Navy on 2 June 1941 at Charleston, South Carolina; and commissioned as USS Markab (AK 31) on 15 June 1941 with Commander Allen D. Brown in command.