Saint Alexander (between 237 and 244 - 337), bishop of Byzantium and first bishop of Constantinople until his death, as the city was then called (Theod. Hist. i. 19) for about 23 years. His consecration, which was variously dated between AD 313 and 317, took place when he was 73 years of age (Socrates Scholasticus Hist. ii. 6; Sozomen Hist. iii. 3).† His feast day is on August 31.

Alexander was highly praised by Gregory Nazianzus (Or. 27) and Epiphanius of Cyprus (adv. Haer. lxix. 10). Theodoret called him an "apostolic" bishop (Hist. i. 3, cf. Phil. 12). In the commencement of the Arian troubles the co-operation of Alexander was specially requested by Alexander of Alexandria (Theod. i. 4).† He was present at the First Council of Nicaea (Soz. ii. 29) although some sources noted that the 117 years old bishop Metrophanes of Constantinople attended the council in Alexander's place.

The Roman emperor Constantine the Great commanded that Arius should be received to communion after he was induced by the Eusebians (Athan. Ep. ad Serap.; Rufinus, Hist. i.) and deceived by the equivocations of Arius (Socr. i. 37). Alexander, though threatened by the Eusebians with deposition and banishment, persisted in his refusal to admit the archheretic to communion, and shut himself up in the church of Irene for prayer in this extremity. Alexander did not long survive Arius (Socr. ii. 6 ; Theod. i. 19). On his deathbed he was said to have designated Paulus as his successor, and warned his clergy against the speciousness of Macedonius.†

Sources

† This article uses text from [http://www.ccel.org/w/wace/biodict/htm/TOC.htm A Dictionary of Christian Biography and Literature to the End of the Sixth Century A.D., with an Account of the Principal Sects and Heresies (http://www.ccel.org/w/wace/biodict/htm/iii.i.xix.htm) by Henry Wace.]