Nicholas Keynes Humphrey (born 27 March 1943) is an English neuropsychologist based in Cambridge, known for his work on evolution of primate intelligence and consciousness. He studied mountain gorillas with Dian Fossey in Rwanda; he was the first to demonstrate the existence of "blindsight" after brain damage in monkeys; he proposed the theory of the "social function of intellect". He is the only scientist to have edited the literary journal Granta.

Humphrey played a significant role in the anti-nuclear movement in the late 1970s and delivered the BBC Bronowski memorial lecture titled "Four Minutes to Midnight" in 1981.

His 10 books include Consciousness Regained, The Inner Eye, A History of the Mind, Leaps of Faith, The Mind Made Flesh, Seeing Red, and Soul Dust. He has received several honours, including the Martin Luther King Memorial Prize, the Pufendorf Medal and the British Psychological Society's book award.

He has been lecturer in psychology at Oxford, assistant director of the Subdepartment of Animal Behaviour at Cambridge, senior research fellow at Cambridge, professor of psychology at the New School for Social Research, New York, and school professor at the London School of Economics.