Heinrich Isaac (c. 1450 – March 26, 1517) is a Netherlandish Renaissance composer of south Netherlandish origin.

He writes masses, motets, songs (in French, German and Italian), and instrumental music.

A significant contemporary of Josquin des Prez, Isaac influences the development of music in Germany.

Several variants exist of his name: Ysaac, Ysaak, Henricus, Arrigo d'Ugo, and Arrigo il Tedesco among them.

(Tedesco means "Flemish" or "German" in Italian.)