William Rees may refer to:
Sports William Rees (rugby) (1899–1968), rugby union and rugby league footballer of the 1920s and 1930s William Lee Rees (1836–1912), English-born New Zealand cricketer, politician and lawyer Billy Rees (1924–1996), association footballer of the 1940s and 1950s
Religious figures William Rees (priest and writer) (1859–1936), earlier Welsh Anglican priest William Jenkins Rees (1772–1855), Welsh cleric and antiquary William Rees (archdeacon of St Asaph) (1905–?), later Welsh Anglican priest
Others William Rees (Liberal politician), in 1390 MP for Norfolk William Hurst Rees (1917–2004), British surveyor and member of the Lands Tribunal William James Rees (1913–1967), British hydroid and cephalopod researcher William E. Rees (born 1943), originator of "ecological footprint" concept William Rees (cinematographer) (1904–1961), American cinematographer William Rees (Gwilym Hiraethog) (1802–1883), writer William Rees (veterinary surgeon) (1928–2018), Chief Veterinary Officer of the United Kingdom, 1980–1988 William Gilbert Rees (1827–1898), explorer, surveyor, and early settler in Central Otago, New Zealand
See also William Rees-Mogg (1928–2012), British journalist, writer and politician William Reese (disambiguation) William Rees-Davies (disambiguation)