Peter Duff Hart-Davis (born 1936), generally known as Duff Hart-Davis, is a British biographer and journalist, who writes (or wrote?) for The Independent newspaper.

He is the elder son of the publisher Sir Rupert Hart-Davis (1907 - 1999), and hence the elder brother of the television broadcaster and author Dr. Adam Hart-Davis. His sister is married to the present Lord Silsoe.

His godfather was the adventurer and writer Peter Fleming (19071971), whose life was written up by Duff Hart-Davis as Peter Fleming: A Biography, published in 1974.