John Koukouzelis

John Koukouzelis Papadopoulos (born c. 1270) was a Byzantine composer, singer and reformer of Byzantine chant, probably born at Dyrrhachium. Educated in the imperial school at Constantinople, he became a principal choir chanter and a favourite of the emperor before withdrawing to the Great Lavra on Mount Athos, where he took the monastic name Ioannikios.

Celebrated for his voice as Angel-voiced, he composed and annotated chants that shaped later Byzantine music, and the Orthodox Church later honoured him as a saint with feast day on 1 October.