J. G. Jeffreys (born 1893), Australian schoolteacher who moved to England and founded Bryanston School in Dorset
•
John R.F. Jeffreys (1918–1941), British mathematician and World War II codebreaker
•
John Gwyn Jeffreys (1809–1885), British conchologist and malacologist
John F. Kennedy | Pope John Paul II | Elton John | John | John Lennon | John Wayne | John McCain | John Kerry | John Cage | Olivia Newton-John | John Williams | John Peel | John Adams | John Steinbeck | John Travolta | John Milton | John Zorn | John Marshall | John Howard | John Singer Sargent | John Ruskin | John Updike | John Maynard Keynes | John Coltrane | John Cleese | St. John's | John Waters | John Lee Hooker | John Huston | John Ford |