William Mackay

William Mackay or MacKay may refer to:
 * William Mackay (artist) (1876–1939), American artist
 * William Andrew MacKay (1929–2013), Canadian lawyer, judge and university president
 * William Paton Mackay (1839–1885), Scottish doctor, Presbyterian minister and hymn writer
 * William MacKay (politician) (1847–1915), physician and political figure in Nova Scotia
 * William Alexander Mackay (1860–1927), Scottish doctor who co-founded Spain's oldest football club, Recreativo de Huelva
 * William John MacKay, Ontario politician