John Koukouzeles was a prominent Byzantine composer, singer, and reformer of chant who lived from approximately 1280 to 1360. Born in Durrës, he received an education at the imperial court in Constantinople, where he became a leading musical authority and a favorite of the emperor. Known as "Angel-voiced" due to his singing talent, he later moved to Mount Athos to live as a monk in the Great Lavra. He is celebrated for developing the melodious kalophonic style of singing, leaving a profound impact on the musical traditions of several Balkan nations.