John Grimes may refer to:
- John Grimes (Quaker) (1802–1875), anti-slavery advocate
- John Grimes (New Zealand bishop) (1842–1915), first Roman Catholic bishop of Christchurch, New Zealand
- John Grimes (bishop) (1852–1922), Roman Catholic bishop
- John Bryan Grimes (1868–1923), North Carolina Democratic politician and farmer
- John Grimes (baseball) (1869–1964), American baseball player
- John Grimes (priest) (1881–1976), Anglican Archdeacon of Northampton
- John Grimes, member of the Irish pop rap duo Jedward
- John Grimes, fictional character created by A. Bertram Chandler
- John Grimes, fictional character in the film Black Hawk Down