Constantine Leichoudes
| Constantine III of Constantinople | |
|---|---|
| Ecumenical Patriarch of Constantinople | |
| Church | Church of Constantinople | 
| In office | 2 February 1059 – 9/10 August 1063 | 
| Predecessor | Michael I of Constantinople | 
| Successor | John VIII of Constantinople | 
| Personal details | |
| Born | Constantine Leichoudes | 
| Died | 9 or 10 August 1063 | 
| Denomination | Eastern Orthodoxy | 
Constantine III of Constantinople (Greek: Κωνσταντίνος Γʹ Λειχούδης; died 9 or 10 August 1063) was the Ecumenical Patriarch of Constantinople from 1059 until his death in 1063.
Born in Constantinople, he was a fellow student of Michael Psellus and John Xiphilinus. He rose to high court offices: appointed protovestiarios, he later became proedros ("president") of the Byzantine Senate and was one of the senior aides of emperors Michael V and Constantine IX. He also became abbot of the imperial Mangana Monastery, and in 1059, following the dismissal of Michael I of Constantinople, he was elected into the patriarchal office, which he held until his death. He is considered a saint of the Eastern Orthodox Church and is commemorated on 29 July.