Guillaume Du Fay (5 August 1397 – 27 November 1474) was a prominent composer and music theorist of the early Renaissance, often described as French or Franco-Flemish. He is considered the leading European composer of his era, with his music widely performed and reproduced. Du Fay was associated with the Burgundian School and had a notable connection with composer Gilles Binchois, although he was not a regular member of the Burgundian chapel.

Du Fay's early life is somewhat obscure, but he was likely the illegitimate child of a priest and received his education at Cambrai Cathedral. His teachers included Nicolas Grenon and Richard Loqueville. Throughout his career, Du Fay worked in various European locations, including Cambrai, Rimini, Pesaro, and Bologna, where he was ordained as a priest. He gained fame and settled in Rome in 1428, joining the papal choir under Pope Martin V and later Pope Eugene IV, composing notable motets such as "Balsamus et munda cera" and "Ecclesie militantis."

In 1436, Du Fay returned to Italy and composed the celebrated motet "Nuper Rosarum Flores" for the consecration of the Florence Cathedral's dome. He later joined the papal court in Bologna and was associated with the House of Este in Ferrara. After serving in various roles, including under Philip the Good in Cambrai, Du Fay returned to Cambrai in 1458, focusing on composing English-inspired cyclic masses. His final years saw him influencing leading musicians like Antoine Busnois and Johannes Ockeghem.

Du Fay's career was marked by extensive travels across Western Europe, contributing to his 'cosmopolitan style' and a vast body of work that encompassed nearly every polyphonic genre of his time. His music was significantly influenced by the contenance angloise, and he is recognized as a leading figure in the first generation of European musicians primarily regarded as composers.