Heinrich Isaac (c. 1450–1517) was a prominent composer of the Renaissance, primarily known for his contributions to sacred music, but he also excelled in secular forms. Born in the Low Countries, he spent much of his career in Italy and later in the service of the Habsburg court in Spain. His genre-spanning repertoire includes masses, motets, and chanson. Notable works by Isaac include the "Missa de Apostolis," a mass setting that showcases his mastery of polyphony, and the secular piece "Innsbruck, ich muss dich lassen," which remains popular in the choral repertoire. His music often features rich textures and intricate counterpoint, reflective of the emerging Renaissance style. Isaac's impact on music is significant; he influenced contemporaries such as Josquin des Prez and later composers through his innovative use of melody and harmony. He also played a crucial role in the transition from the medieval to the Renaissance musical idiom, helping to establish the foundations of polyphonic music that would flourish in the following centuries. His works are still performed today, underscoring his enduring legacy in the history of Western classical music.