Atticus of Constantinople was an early 5th-century archbishop who led the see of Constantinople from 406 until his death in 425. Born in Sivas, he rose through the ecclesiastical ranks to become a significant political and religious figure within the Byzantine Empire. He is historically noted for his intense rivalry with John Chrysostom, whom he helped depose, and for his efforts to expand the authority of his office. Beyond his administrative role, he was a defender of orthodoxy against various heresies and contributed to early theological developments regarding the Virgin Mary.