John Sinclair may refer to:
Politicians
edit- Sir John Sinclair, 1st Baronet (1754–1835), politician and writer on agriculture and finance
- John Sinclair (Australian politician) (1807–1890), MLA for North Melbourne
- John Mitchell Sinclair (1819–1890), South Australian politician
- Sir John Sinclair, 3rd Baronet (1825–1912), Scottish politician and landowner
- John Sinclair (mayor) (1827–1906), mayor of Brisbane
- John Sinclair (Ayr Burghs MP) (1842–1892), Liberal MP for Ayr Burghs
- John Howard Sinclair (1848–1924), Canadian politician
- John Sinclair (New Zealand politician) (1850–1940), member of the New Zealand Legislative Council
- John Sinclair, 1st Baron Pentland (1860–1925), Scottish politician
- John Ewen Sinclair (1879–1949), Canadian politician
- John William Sinclair (1879–?), politician in Ontario, Canada
- John Sinclair, 3rd Viscount Thurso (born 1953), British Member of Parliament for Caithness and Sutherland
Music and poetry
edit- John Sinclair (poet) (1941–2024), American poet and political activist
- John Sinclair (musician) (born 1952), British musician, played with Ozzy Osbourne and Uriah Heep
- Yasus Afari (born 1962), Jamaican dub poet, born John Sinclair
- Johnny Sinclair, musician in the bands The Pursuit of Happiness and Universal Honey
- "John Sinclair", a song by John Lennon on the Some Time in New York City album
Actors
edit- John Sinklo, sometimes known as John Sinclair, English renaissance actor
- John West Sinclair (1900–1945), American silent-screen actor
- John Gordon Sinclair (born 1962), Scottish actor
Others
edit- John Sinclair, 3rd Earl of Caithness (died 1529), Scottish nobleman
- John Sinclair (bishop) (died 1566), Ordinary Lord and later Lord President in the Court of Session
- John Sinclair, Master of Caithness (died 1576), Scottish nobleman
- John Sinclair, 10th Lord Sinclair (died 1676), Scottish nobleman
- John Sinclair, 23rd Lord Herdmanston, Scottish noble
- John Sinclair, 8th Earl of Caithness (died 1705), Scottish nobleman
- John Sinclair, Lord Murkle (died 1755), Scottish judge
- John Sinclair, 11th Earl of Caithness (died 1789), Scottish noble
- John Sinclair (archdeacon of Middlesex) (1797–1875), Scottish Archdeacon of Middlesex
- John Sinclair (interpreter), Canadian clergyman and interpreter among the Cree in the 19th century
- John Sinclair (New Zealand carpenter) (1843–1925), New Zealand carpenter, builder, station manager and harbourmaster
- John Sinclair (archdeacon of Cirencester) (1853–1919), British clergyman, Archdeacon of Cirencester
- John Sinclair (physician) (1868–1940), British physician, Chief Medical Officer to the General Post Office
- John Houston Sinclair (1871–1961), British civil servant in Zanzibar
- Sir John Sinclair (British Army officer) (1897–1977), British Army general, head of the Secret Intelligence Service
- John S. Sinclair (1897–1972), American lawyer and financier
- John Sinclair (Lord Lieutenant of Caithness) (1898–1979), Scottish Lord Lieutenant
- John McHardy Sinclair (1933–2007), British linguist
- John Henderson Sinclair (1935–2009), British scholar and academic
- John Sinclair (environmentalist) (1939–2019), Australian environmentalist
- Jackie Sinclair (1943–2010), Scottish footballer
- John Sinclair (footballer) (born 1948), Australian rules footballer for Essendon
- John Sinclair (German fiction), fictional protagonist of a popular German "penny dreadful"
- John Sinclair (sociologist) (born 1944)