Richard Darwin Keynes, CBE, FRS ( ; 14 August 1919 – 12 June 2010) was a British physiologist. The great-grandson of Charles Darwin, Keynes edited his great-grandfather's accounts and illustrations of Darwin's famous voyage aboard into The Beagle Record: Selections From the Original Pictorial Records and Written Accounts of the Voyage of the H.M.S. Beagle, which won praise from the New York Review of Books and The New York Times Book Review. Randal Keynes (1948-2023), Roger Keynes (b. 1951), and Simon Keynes (born 1952).
During the war, Keynes served as a temporary experimental officer at the Anti-Submarine Establishment and Admiralty Signals Establishment (1940–45), returning to Cambridge after the war to complete his degree (1st Class, Natural Science Tripos Part II, 1946).