John MacKay, Mackay, or McKay may refer to:

• John Bain Mackay (1795–1888), nurseryman based in Clapton, London
• John MacKay (journalist) (born 1967), Scottish television journalist and newscaster
• John D. Mackay (1909–1970), Orcadian man of letters
• John Henry Mackay (1864–1933), Scottish writer, anarchist, thinker and homosexual activist
• John Victor Mackay (1891–1945), American art director
• John Yule Mackay (1860–1930), Scottish anatomist and Principal of University College, Dundee
• John Mackay (poet) (1656–1754), Scottish Gaelic poet known as Am Pìobaire Dall
• John McKay (director), British film and television director
• John McKay (mathematician) (1939–2022), mathematician at Concordia University
• John McKay (musician), British guitarist and former member of Siouxsie & the Banshees
• John P. McKay, American historian and professor, author of A History of Western Society
• John McKay (pianist) (born 1938), Canadian-American pianist
• John Sturgeon Mackay (1843–1914), Scottish mathematician

• John Calder Mackay (1920–2014), American real estate developer
• John Mackay (industrialist) (1774–1841), ship master and industrialist in Boston, Massachusetts
• John William Mackay (1831–1902), American capitalist

• John Frederick MacKay (1873–1930), Scottish recipient of the Victoria Cross
• John McKay (attorney) (born 1956), United States Attorney for the Western District of the state of Washington
• John B. McKay (1922–1975), test pilot
• John McKay (police officer) (1912–2004), British police inspector

• John Mackay, 11th of Strathnaver (died 1529), chief of the ancient Clan Mackay
• John MacKay, Baron MacKay of Ardbrecknish (1938–2001), Scottish Conservative Member of Parliament for Argyll, 1979–1987
• John George MacKay (1893–1974), farmer and political figure on Prince Edward Island
• John Keiller MacKay (1888–1970), 19th Lieutenant Governor of Ontario, Canada, 1957–1963
• John McKay (English politician) (1883–1964), British Labour Party MP for Wallsend, 1945–1964
• John McKay (politician, born 1841) (1841–1918), Ontario physician and political figure
• John McKay (Ontario politician, born 1948) (born 1948), member of the Canadian parliament
• John P. MacKay, Ontario politician
• John McKay (New Brunswick politician) (born 1948), former Speaker of the Legislative Assembly of New Brunswick and mayor of Miramichi, New Brunswick
• John McKay (Northern Ireland politician) (born 1945), member of the Northern Ireland Constitutional Convention
• William John MacKay, Ontario politician

• John Mackay (cricketer) (born 1937), Australian cricketer
• John Mackay (rugby league), Australian rugby league player
• John McKay, co-founder of the Gaelic Athletic Association
• John McKay (footballer, born 1898) (1898–?), Scottish footballer
• John McKay (1950s footballer), Scottish football player
• John McKay (American football) (1923–2001), American football coach
• John McKay Jr. (born 1953), American football wide receiver

• John Mackay (Australian pioneer) (1839–1914), founder of the city of Mackay, Australia
• John A. Mackay (1889–1983), Scottish missionary and founder of the Anglo-Peruvian School in Lima, Peru
• John Calvin MacKay (1891–1986), Free Church of Scotland minister
• John Ross Mackay (1915–2014), Canadian geographer

• Jack McKay (disambiguation)
• John Mackey (disambiguation)
• John Mackie (disambiguation)