Stephen I of Constantinople, also known as Stephen the Macedonian, was a 9th-century cleric who served as the Ecumenical Patriarch from 886 until his death in 893. Born in Constantinople, he was the son of Eudokia Ingerina and was likely the biological child of Emperor Michael III. Following his castration by Basil I, he entered monastic life. His brother, Emperor Leo VI, appointed him to the patriarchate at the age of 19, marking a significant period in the religious history of the Byzantine Empire.