John Thornycroft

John Thornycroft may refer to:
 * Sir John Thornycroft, 1st Baronet (1659–1725), English barrister-at-law
 * John Edward Thornycroft (1872–1960), British civil engineer
 * John Isaac Thornycroft (1843–1928), British shipbuilder
 * John I. Thornycroft & Company Limited, the shipbuilding company named after him