The Bishop of Alexandria, who was one of the four great patriarchs of the Church, was born in 295 AD and died in 373 AD.  He was the bitterest opponent of Arius and his proclamation  of the parity of Christ’s nature within the Trinity.  That teaching was ultimately rejected by the Council of Nicaea in 325 AD.  Because of his over-zealousness, Emperor Constantine banished Athanasius several times (to Rome and to Trier).
Athanasius’ biography of St. Antonius Eremita contributed greatly to the promotion of monkhood.
Other representations are not found in Occidental art until 1773 in a fresco of Bartolomeo Altomonto in the hospital of the town of Phyrn, Austria, where he is represented with a long beard and robes conforming to those of Greek bishops.