William McCoy or MacCoy may refer to:
W. F. McCoy (1886–1976), Speaker of the Northern Ireland House of Commons
William McCoy (bootlegger) (1877–1948), American rum-runner during Prohibition
William McCoy (congressman) (died 1864), American politician and member of Congress William McCoy (mutineer) (c. 1763–1798), Scottish mutineer on HMS Bounty William McCoy (Oregon politician) (1921–1996), American politician and member of the Oregon Legislative Assembly William D. McCoy (1853–1893), American diplomat William F. MacCoy (1840–1914), lawyer and politician in Nova Scotia, Canada William J. McCoy (composer) (1848–1926), American composer William J. McCoy (Mississippi politician) (1942–2019), American politician and Speaker of the Mississippi House of Representatives William John McCoy (1834–1897), American politician and member of the Wisconsin State Assembly