William Macdonald or MacDonald or McDonald may refer to:
Academics
William MacDonald (Christian author) (1917–2007), American Plymouth Brethren scholar and theologian; president of Emmaus Bible College
William Macdonald (historian) (1863–1938), American journalist and historian
William Andrew McDonald (1913–2000), American archaeologist
William Bell Macdonald (1807–1862), Scottish linguist
William L. MacDonald (1921–2010), American historian of Roman architecture
Arts and entertainment
Will McDonald (actor), Australian actor
William Colt MacDonald (1891–1968), American writer of Westerns
William H. MacDonald (1849–1906), American baritone and actor
William J. Macdonald (filmmaker) (born 20th century), American film and television producer
Will Macdonald (born 1966), British television producer, executive and writer
Law enforcement and military
William MacDonald (RAF officer) (1908–1984), British air marshal
William Hixon McDonald (senior) (c. 1815–1869), Australian soldier-settler and gold miner
William Jesse McDonald (1852–1918), Texas Ranger
William Myron MacDonald (1890–1958), American-born Canadian flying ace
William Rae Macdonald (1843–1923), Scottish officer of arms
Politicians
William McDonald (Canadian politician) (1837–1916), from Nova Scotia
William McDonald (Ontario politician), from Ontario
William McDonald (Australian politician) (1911–1995), speaker of the Victorian Legislative Assembly
William MacDonald (New Zealand politician) (1862–1920), cabinet minister and briefly Leader of the Opposition
William Alexander Macdonald (1860–1946), Canadian politician; from Manitoba
William Archibald Macdonald (1841–1911), Irish nationalist politician and MP
William C. McDonald (governor) (1858–1918), American politician; governor of New Mexico
William Chisholm Macdonald (1890–1946), Liberal Party member of the Canadian House of Commons
William H. McDonald (1899–1967), American politician; Texas land commissioner
William John Macdonald (1832–1916), Canadian merchant and politician
William Josiah MacDonald (1873–1946), American politician; from Michigan
William Madison McDonald (1866–1950), African-American politician and businessman
William Ross Macdonald (1891–1976), Canadian lawyer and statesman; from Ontario
William Walter McDonald (1844–1929), Canadian politician; from the Northwest Territories
Religious figures
William Macdonald (priest) (1783–1862), British; archdeacon of Wilts
William Joseph McDonald (1904–1989), Irish-born bishop of the Catholic Church in the United States
Sports
William MacDonald (footballer) (1911–1978), Scottish footballer and Royal Navy officer
William Macdonald (jockey) (1800–1856), British; winner of the 1840 Epsom Derby
William McDonald (bowls) (1885–?), Canadian lawn bowls international
Will McDonald (basketball) (born 1979), American basketball player
Will McDonald IV (born 1999), American football player
Willie McDonald (1905–1979), Scottish footballer
Willie McDonald (footballer, born 1883) (1883–after 1914), Scottish footballer
William Macdonald (rugby union) (1861–1941), Scotland international rugby union player
Others
Will McDonald (journalist) (born 1979), Australian television journalist
William MacDonald (serial killer) (1924–2015), Australian serial murderer
William Christopher Macdonald (1831–1917), Canadian tobacco manufacturer and philanthropist
William Hixon McDonald (junior) (1840–1898), Australian miner, political candidate and pioneer
William Johnson McDonald (1844–1926), American banker; endowed an astronomical observatory
William Sutherland Macdonald (1897–1990), Scottish physician; principal medical officer at the Ministry of Health
William W. McDonald (born 20th century), American rancher and conservationist
William James Macdonald (1851–1941), Scottish mathematician and schoolteacher