John Smyth
John Smyth may refer to:
- John Smyth (merchant), Bristol businessman and mayor
- John Smyth (English theologian), considered the earliest Baptist
- John Smyth (priest), Anglican archdeacon in Ireland
- John Smyth (Master of Pembroke), clergyman and Master of Pembroke College, Oxford
- John Ferdinand Smyth Stuart, until 1793 John Ferdinand Smyth, Scottish physician, soldier, and author
- John Smyth (1748–1811), British member of parliament for Pontefract
- John Smyth (sculptor), Irish sculptor
- John Henry Smyth, British member of parliament for Cambridge University
- John Smyth (minister), Scottish minister in the Free Church of Scotland
- John Rowland Smyth, British soldier
- John [George Smyth (1815–1869)], Conservative member of parliament for the City of York
- John [Henry Greville Smyth] 1836–1901), English naturalist and collector
- John Paterson Smyth, Canadian Anglican priest, Archdeacon of Montreal
- Sir John Smyth, 1st Baronet, British MP, Privy Counsellor in 1962, recipient of the Victoria Cross during the First World War
- John Smyth (snooker referee)
- John Smyth (barrister), British QC, Christian lay minister, and child abuser
- John Smyth (footballer), Irish former professional footballer