From Catholic Culture:
St. Athanasius, Bishop of Alexandria and a great defender of the orthodox faith, throughout his life opposed the Arian heresy. By denying the Godhead of the Word the Arians turned Christ into a mere man, only higher in grace than others in the eyes of God. St. Athanasius took part in the Council of Nicea in 325 and until the end remained a champion of the faith as it was defined by the Council. In him the Church venerates one of her great Doctors. He was subjected to persecutions for upholding the true teaching concerning the person of Christ and was sent into exile from his see no less than five times. He died at Alexandria in 373 after an episcopate of forty-six years. Read more here.