Johannes Ockeghem (also Jean de, Jan; surname Okeghem, Ogkegum, Okchem, Hocquegam, Ockegham; other variant spellings are also encountered) (1410/1425 – February 6,[2] 1497) was the most famous composer of the Franco-Flemish School in the last half of the 15th century, and is often considered the most influential composer between Guillaume Dufay and Josquin des Prez. In addition to being a renowned composer, he was also an honored singer, choirmaster, and teacher. Source : Wikipedia