Guillaume Du Fay (c. 1397–1474) was a French composer and music theorist.
Dufay or du Fay may also refer to:
People Charles François de Cisternay du Fay (1698–1739), French chemist Claude Dufay (1926–2001), French entomologist, see Argyrogrammatini Jean Dufay (1896–1967), French astronomer Dufay (crater), a crater on the Moon named after Jean Dufay Marie-Guite Dufay (born 1949), French politician Rick Dufay (born 1952), French-American guitarist, Aerosmith DuFay A. Fuller (1852–1924), American businessman and politician
Toponyms Dufay River, a tributary of lake Buies, in Québec, Canada
See also Dufay Collective, an early-music ensemble from the United Kingdom, specializing in Medieval and Renaissance music and named after Guillaume Du Fay Dufaycolor, an additive color process for motion pictures