Orthodox Saints of the Pre-Schism See of Rome
AMBROSE of FERENTINO, the patron saint of Ferentino in present-day Lazio central Italy, St. Ambrose, a fourth-century centurion in the Roman army, was subjected to torture and then executed for his faith during the Diocletianic Persecution (303–313). In 1108 the relics of St. Ambrose were enshrined in the Ferentino Cathedral (Duomo di Ferentino; Basilica Cattedrale dei Santi Giovanni e Paolo).
ARMAGILLUS (ARMEL) of BRITTANY, a Welsh missionary to Brittany (north-western France), and cousin of St. Samson of Dol (28th July), St. Armagillus was one of the missionaries who founded the abbey which came to be called the Abbey of St. Armel of Boschaux (abbaye Saint-Armel-des-Boschaux) in present-day Ille-et-Vilaine, Brittany, and another abbey at Ploërmel also in Brittany. In addition St. Armagillus is commemorated in the name of civil parish and village of St. Erme in Cornwall, England.
ELEUTHERIUS, succeeding St. Drouet of Auxerre (8th November) in 533 as Bishop of Auxerre in Burgundy (east-central France), St. Eleutherius served the See of Auxerre until his repose in 561.
SIMPLICIAN of MILAN, a close friend and advisor of St. Ambrose of Milan (7th December), whom he succeeded as Bishop of Milan in 397. St. Simplician reposed in 400.
STEPHEN of HUNGARY, crowned in 1001 the first King of Hungary. King St. Stephen and his wife Gisela, continued the work they had already started of enlightening their people. He organised dioceses and founded monasteries (among them Esztergom, the primatial see; and Pannonhalma Abbey, which still exists and is a UNESCO World Heritage Site). King St. Stephen reposed in 1038, and is one of the most popular saints in Hungary, and feast day is celebrated as a state holiday commemorating the foundation of the nation.
TITUS the DEACON, a deacon who was ministering to the beleaguered population. St. Titus was martyred at some point during the siege and subsequent sack of Rome (408–410) by Alaric I, King of the Visigoths (r. 395–410) and his army.
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”.
In many cases there are several spelling versions of the names of saints from the British Isles. I use the Oxford Dictionary of National Biography version as the primary version with the more prevalent version in parenthesis e.g. Ceadda (Chad) of Lichfield.