Sir Martin John Evans (born 1 January 1941, Stroud, Gloucestershire) is a British geneticist.
His first success was with Matthew Kaufman. In 1981 they were the first to grow embryonic mice stem cells in a laboratory.
Evans, Oliver Smithies and Mario Capecchi discovered a technique in genetic engineering. It is known as homologous recombination of transgenic DNA. This is important because it is the most reliable method of changing animal genomes.
The three put this to use in two more inventions: gene targeting and knockout mice, and were jointly awarded the Nobel Prize in Physiology or Medicine in 2007.