John McDonnell (born 1951) is a British Labour Party politician who has been the Member of Parliament for Hayes and Harlington since 1997.

John McDonnell and variations may also refer to:

Politicians

• John Macdonell of Greenfield (1785–1812), Canadian lawyer and politician, aide-de-camp to Isaac Brock
• "Spanish" John MacDonell (Revolutionary War loyalist) (1728–1810), United Empire Loyalist and early Canadian settler
• John MacDonell (political strategist), past President of the Nova Scotia Progressive Conservative Party in Canada
• John MacDonell (Nova Scotia politician) (born 1956), NDP MLA in Nova Scotia
• John McDonell (American politician) (1780–1846), member of the Michigan Senate in the first years of Michigan's statehood
• John McDonell (Le Prêtre) or Macdonell (1768–1850), known as Le Prêtre, political figure in Upper Canada
• John Alexander MacDonell (1854–1912), Canadian politician

Sports

• John Macdonell (rugby league), Australian rugby league footballer, see List of Canterbury-Bankstown Bulldogs players
• John McDonnell (coach) (1938–2021), track coach for the Arkansas Razorbacks
• John McDonnell (footballer) (born 1965), former Irish footballer and football manager
• Johnny McDonnell (1885–?), Irish footballer
• Johnny McDonnell (Gaelic footballer), player for Dublin
• John McDonell (c. 1758–1809), captain in Butler's Rangers and MLA for Glengarry County, Ontario, Canada

Arts and entertainment

• John Macdonell, American radio producer and host, see WUWF
• John McDonnell (playwright), Irish playwright and journalist
• John McDonnell (producer), Irish film producer

Others

• John Macdonnell (1821–1902), Irish Dean of Cashel
• Sir John Macdonell (judge), (1846–1921), English editor of State trials
• John MacDonell (British Army officer) (1899–1944), British colonel
• John McDonnell (businessman) (born 1938), chairman and CEO at McDonnell Douglas and Boeing
• John McDonnell (trade unionist) (born 1943), former Irish trade union leader
• John MacDonnell (surgeon) (1796–1892), Irish surgeon