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Cyriacus I of Byzantium | |
|---|---|
| Bishop of Byzantium | |
| Installed | 217 |
| Term ended | 230 |
| Predecessor | Philadelphus of Byzantium |
| Successor | Castinus of Byzantium |
| Personal details | |
| Denomination | Early Christianity |
Cyriacus I (Greek: Κυριακός; died 230) succeeded Philadelphus as Bishop of Byzantium and governed the local church for 13 years. In some catalogues appears under the name Cyrillianus.