MARCUS, bishop of Aretusa. — A follower of Arius, he took part in the Council of Antioch in 341 and the following year was part of the delegation that went to Trier to meet Constantius.
In 343 he was with the Eastern faction gathered at Philippopolis, having abandoned the Council of Serdica, and he also took part in the Synod of 351 against Photinus. In 359 he drafted the Homoian formula approved at the Council of Rimini and then participated in the Council of Seleucia. During the pagan restoration under Julian the Apostate he was subjected to atrocious torments by his fellow citizens because he had destroyed a temple. He was still alive in 363 but must have died shortly after.
St. Gregory Nazianzen and Theodoret praise him for his religious zeal, extol his wisdom and piety, and describe him as filled with every virtue. The Greek Church honors him as a martyr and commemorates him on 28 March.