John Harmer may refer to:
John Harmer (mayor), mayor of Williamsburg, Virginia, 1737–1738 John L. Harmer (born 1934), former California politician John Harmer (bishop) (1884–1944), Anglican bishop
See also John Harmar (c. 1555–1613), English classical scholar John Harmar (philologist) (1594?–1670), English cleric and academic