William Massey (1856–1925) was prime minister of New Zealand.
William Massey may also refer to: Bill Massey (baseball) (1871–1940), baseball player in 1894 Bill Massey (softball) (1936–2020), New Zealand softball player, coach and umpire William Massey (cricketer) (1846–1899), played cricket for Somerset and Lancashire William Massey (rower) (1817–1898), rowed and played cricket for Cambridge University William A. Massey (politician) (1856–1914), U.S. senator William A. Massey (mathematician) (born 1956), American mathematician William Clifford Massey (1917–1974), American anthropologist William Nathaniel Massey (1809–1881), British author and politician William S. Massey (1920–2017), American mathematician
See also William Massie (1718–1751), Virginia planter and politician