John Jeffreys

John Jeffreys may refer to:


 * John R.F. Jeffreys (1916–1944), British mathematician and World War II codebreaker
 * John Gwyn Jeffreys (1809–1885), British conchologist and malacologist
 * J. G. Jeffreys (1893–?), Australian schoolteacher who moved to England and founded Bryanston School in Dorset
 * John Jeffreys (died 1689), British Member of Parliament for Brecon and Breconshire
 * John Jeffreys (died 1715) (c. 1659–1715), British Member of Parliament for Breconshire, Marlborough and Radnorshire
 * John Jeffreys (1706–1766), British Member of Parliament for Breconshire and Dartmouth