Galeazzo Maria Sforza (January 24, 1444 – December 26, 1476) was Duke of Milan. He was a member of the Sforza family of Milanese rulers, famous as patrons of the arts and music. He was also famous for being lustful, cruel and tyrannical.

Galeazzo was born to Francesco Sforza and Bianca Maria Visconti. He married into the Gonzaga family, and on the death of his wife Dorotea married again, to another Gonzaga, the daughter of Lodovico I of Mantua . Galeazzo was murdered on December 26, 1476, on the steps of Milan cathedral, by a group of three noblemen where were evidently attempting to re-stage the murder of Julius Caesar.

Galeazzo was famous as a patron of music. Under his direction, financial backing and encouragement, his chapel grew into one of the most famous and historically significant musical ensembles in Europe. Composers from the north, especially the Franco-Flemish composers from the present-day Low Countries, came to sing in his chapel and write masses, motets and secular music for him. Some of the figures associated with the Sforza chapel include Alexander Agricola, Johannes Martini, Loyset Compère, and Gaspar van Weerbeke. Most of the singers at the chapel fled after Galeazzo's murder, however, and took positions elsewhere; soon there was a rise in musical standards in other cities such as Ferrara as a result.

On Galeazzo's death, his son Gian Galeazzo Sforza became Duke. His daughter Bianca Maria Sforza (1472-1510) married Maximilian I, Holy Roman Emperor, in 1493.