Sainted Peter, Bishop of Sebasteia, was a brother of Sainted Basil the Great and Sainted Gregory of Nyssa (Comm. 1 January and 10 January). And in his upbringing a large part was played by his older sister, Saint Macrina (Comm. 19 July).
Sainted Basil the great consecrated Saint Peter as presbyter, and after the death of Saint Basil he was made bishop of Sebasteia (in Armenia). Saint Peter was present at the Second OEcumenical Council in the year 381, convened at Constantinople against the heresy of Macedonias.