Memnon of Ephesus was a 5th-century metropolitan bishop who played an active role during the third ecumenical council. As a prominent leader in Ephesus, he acted as a close ally to Cyril of Alexandria during the theological disputes of the era. Beyond his administrative duties, he is recognized as a writer and a theologian. His tenure was marked by significant ecclesiastical politics, including his involvement in the formal protests against John of Antioch during the council sessions.