Sir Peter Brian Medawar OM CBE FRS (/ˈmɛdəwər/; 28 February 1915 – 2 October 1987) was a British biologist born in Brazil, whose work on graft rejection and the discovery of acquired immune tolerance was fundamental to the practice of tissue and organ transplants. He was awarded the 1960 Nobel Prize in Physiology or Medicine with Sir Frank Macfarlane Burnet. For his works he is regarded as the "father of transplantation". He is remembered for his wit in real life and popular writings.