Sir Peter Brian Medawar OM CBE FRS (/ˈmɛdəwər/; 28 February 1915 – 2 October 1987) was a British biologist and writer, whose works on graft rejection and the discovery of acquired immune tolerance were fundamental to the medical practice of tissue and organ transplants. For his scientific works he is regarded as the "father of transplantation". He is remembered for his wit both in person and in popular writings.