Orthodox Saints of the Pre-Schism See of Rome
15th August
ALIPIUS (ALYPIUS) of TAGASTE, a disciple and lifelong friend of St. Augustine of Hippo (28th August), with whom he was baptised by St. Ambrose of Milan (7th December) on the eve of Pascha 387. Following his return to Africa, St. Alipius spent some time living as a hermit, and then went on a pilgrimage to the Holy Land. He once again returned to Africa, and circa 393 was consecrated Bishop of Tagaste in Africa Proconsularis (present-day Souk Ahras, Algeria). St. Alipius reposed circa 430.
ALTFRID ALFRED of HILDESHEIM, a member of the Saxon nobility and leading figure in his own right, St. Altfrid served as Bishop of Hildesheim (northern Germany) from 851 until his repose in 874, prior to which is seems he was a monk at Corvey Abbey (Fürstabtei Corvey). St. Altfrid founded Essen Abbey (Stift Essen), in the present-day German state of North Rhine-Westphalia, for noble women, and also served as a close adviser to Louis II, King of the East Franks (r. 843–876).
ARDUINUS of RIMINI, a parish priest in Rimini (northern Italy), who at one point lived as a hermit. St. Arduinus later entered the Abbey of St. Gaudentius of Rimini (San Gaudenzio di Rimini), where he reposed in 1009.
TARSICIUS, (Third Century), the only information on the life of St. Tarsicius comes from a poem composed in his honour by Pope Damasus I (r. 366–384) at least a century later. In this poem it is said that St. Tarsicius, whilst taking Communion to prisoners, was attacked by a mob of heathens, choosing to die rather "than surrender the Sacred Body [of Christ] to the raging dogs".
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”.
Details of British Saints excerpted from Orthodox Saints of the British Isles.
Details of continental saints from these sources.
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.