John Duff (disambiguation)
John Duff was a Canadian race car driver.
John Duff may also refer to:
- John Duff (counterfeiter), American counterfeiter, hunter, and scout
- John Duff (singer), American pop singer
- John B. Duff, former commissioner of The Chicago Public Library
- John Finlay Duff, captain of ship Africaine and businessman in South Australia
- John Wight Duff, Scottish classicist and academic