Serapion of Thmuis was a fourth-century Egyptian ascetic who became bishop of Thmuis, a city in the Nile Delta of Lower Egypt. Formed in the monastic life as a companion and disciple of Anthony the Great, he was later raised to the episcopate, and from that office became one of the foremost allies of Athanasius of Alexandria in the struggle against Arianism. He is commemorated on March 21. He should not be confused with Serapion the Sindonite, the wandering anchorite commemorated on May 14.
Beyond his role in the doctrinal conflicts of his day, Serapion is remembered as a writer. Jerome, in his work On Illustrious Men, records that he was given the appellation 'Scholasticus' — the Scholastic — on account of his learning. His name is attached to a treatise against the Manichaeans and, most notably, to a collection of liturgical prayers known as the Euchologion or Sacramentary of Serapion, an early witness to the worship of the Egyptian church.
Sources place his episcopate from about 339 until his death around 358, and report that he was exiled by the Arian party in the course of the controversy. His close ties to both Anthony and Athanasius made him a connecting figure between the desert monasticism of Egypt and the dogmatic battles waged from the see of Alexandria.
