Athanasius I of Alexandria (Athanasius the Great)

Serving as deacon to Bishop Alexander at the First Council of Nicaea in 325 CE, Athanasius articulated the term homoousios (consubstantial). Succeeding to the patriarchal throne, he endured seventeen years of exile under four Roman emperors who demanded compromises with Arian factions.

During periods of hiding in the Egyptian desert with Saint Antony, he wrote the seminal Life of Saint Antony, which ignited Christian monasticism across the Mediterranean basin, and penned the 367 CE Festal Letter listing the 27 books of the New Testament canon.