William Castle (1914–1977) was an American film director, producer, and actor.
William Castle may also refer to:
William Castle (shipbuilder) (c. 1615–1681) English shipbuilder for the Royal Navy William Castle (tenor) (1836–1909), English tenor active in the United States William B. Castle (1814–1872), American politician from Ohio William Bosworth Castle (1897–1990), American physician and physiologist William E. Castle (1867–1962), American geneticist William Richards Castle (1849–1935), lawyer, politician and Attorney General of Hawaii William Richards Castle Jr. (1878–1963), U.S. educator, diplomat and ambassador to Japan
See also "William Castle", song by Jay Chou in the 2001 album Fantasy