Sewall Green Wright (21 December 1889 – 3 March 1988) was an American geneticist. He was a founder of population genetics, and contributed to evolutionary theory. He also did original work in statistics in a field called path analysis.
With R.A. Fisher and J.B.S. Haldane, he was a founder of theoretical population genetics. He is the discoverer of the inbreeding coefficient and of methods of computing it in pedigrees. He extended this work to populations, calculating the degree of inbreeding of members of populations as a result of random genetic drift. Together with Fisher, he pioneered methods for calculating the distribution of gene frequencies among populations as a result of the interaction of natural selection, mutation, migration and genetic drift. The work of Fisher, Wright, and Haldane on theoretical population genetics was a major step in the development of the modern evolutionary synthesis of genetics with evolution. Wright also made contributions to mammalian genetics and biochemical genetics.