Philippe de Vitry (31 October 1291 – 9 June 1361) was a French composer, music theorist and poet. He was an accomplished, innovative, and influential composer, and may also have been the author of the Ars Nova treatise. He was widely acknowledged as the greatest musician of his day, with Petrarch writing a glowing tribute, calling him: "...the keenest and most ardent seeker of truth, so great a philosopher of our age."