Proterius was Patriarch of Alexandria from 451 to 457 and is venerated as a hieromartyr for upholding the Christological definition of the Fourth Ecumenical Council against the Monophysite party that dominated the Egyptian church of his day. He had served as a priest in Alexandria under the previous patriarch Dioscorus, and the tradition remembers him for a strict and virtuous life and an open opposition to the Monophysite teaching. He is commemorated on February 28.
At the Council of Chalcedon in 451 the heresy of Eutyches was condemned and Dioscorus was deposed; Proterius was elevated to the patriarchal throne of Alexandria in his place. Because the Alexandrian church was predominantly anti-Chalcedonian, his elevation was violently opposed, and according to the historical sources he was met by rioting upon his accession. His patriarchate thus marks the beginning of the lasting schism in Alexandria between the supporters of Chalcedon and its opponents.
After the death of the emperor Marcian, who had supported the Chalcedonian settlement, the opposition party rose against Proterius and in 457 set up a rival patriarch, Timothy Aelurus. Proterius was killed during this upheaval. The accounts of his death differ among the early historians: by one tradition he was slain by a mob of his opponents, while another attributes his death to the Byzantine garrison in the city. The Orthodox synaxarion relates that he was found hiding in a baptistry on Great and Holy Saturday and killed together with six companions, after which his body was abused and burned. He is honored as a saint and hieromartyr by the Eastern Orthodox Church and by the Roman Catholic Church.
