John Slater may refer to:
- John Slater (industrialist) (1776–1843), (American) father of John Fox Slater, brother and partner of Samuel Slater
- John Fox Slater (1815–1884), American philanthropist, son of John Slater (industrialist)
- John Slater (art director) (1877–1914), art director at Doulton's Burslem factory
- John Slater (New Zealand politician), former President of the New Zealand National Party and current President of Citizens and Ratepayers Now
- John Slater (British politician) (1889–1935), British Conservative MP for Eastbourne, 1932–1935
- John Slater (Canadian politician) (1952–2015), Member of the Legislative Assembly of British Columbia
- John J. Slater Jr. (1925–1998), American lawyer and politician in Massachusetts
- John Slater & Co. of Forestdale, Rhode Island