John Maynard Smith, FRS (6 January 1920 – 19 April 2004) was a British theoretical evolutionary biologist and geneticist. Originally an aeronautical engineer during the Second World War, he then took a second degree in genetics under the well-known biologist J.B.S. Haldane. Maynard Smith was instrumental in the application of game theory to evolution and theorized on other problems such as the evolution of sex and signalling theory.