Glenn Herbert McCarthy (December 25, 1907 – December 26, 1988) was an American oil tycoon. The media often referred to him as "Diamond Glenn" and "The King of the Wildcatters". McCarthy was an oil prospector and entrepreneur who owned many businesses in various sectors of the economy. McCarthy founded the Shamrock Hotel in Houston, which garnered him national fame and inspired the fictional character Jett Rink in Edna Ferber's 1952 novel Giant which, in 1956, became a film, which starred James Dean in the role.