John Mortimer (1923–2009) was a British writer. John Mortimer may also refer to: * John B. Mortimer, Hong Kong judge * Jack Cade, leader of the Kent rebellion * , in heavy metal band Holocaust * for Northamptonshire * John Robert Mortimer (1825–1911), archaeologist * John Mortimer (agriculturalist) (1656–1736), English merchant and writer on agriculture * John Hamilton Mortimer (1740–1779), British painter and printmaker * John Jay Mortimer (1933–2013), American financier