13 December (30 November O.S.):
- CASTULUS AND EUPREPIS, martyrs in Rome.
- CONSTANTIUS, a fifth century priest in Rome who opposed the Pelagians, and under whom he suffered greatly.
- TROJAN (TROYEN), a priest in Saintes, where he later became bishop after St. Vivian (28th August). He reposed in 533.
- TUDWAL (TUGDUAL), a Welsh monk who went to Brittany and became Bishop of Tréguier. He reposed circa 564; and three places in the Lleyn Peninsular in Gwynedd recall him and his relics are still honoured in Tréguier.
* - Prior to the Schism the Patriarchate of Rome was Orthodox and fully in communion with the Orthodox Church. As Saint John of Shanghai and San Francisco +1966 said "The West was Orthodox for a thousand years, and her venerable Liturgy is far older than any of her heresies."