Cyriacus I of Byzantium (Greek: Κυριακός; died 230) succeeded Philadelphus of Byzantium as bishop of Byzantium and governed the local church for 13 years (217 – 230); in some catalogues appears under the name Cyrillianus or Kyriacos. Fordham University website, History Department, Bishops/Patriarchs of Constantinople
Notes and references
Bibliography Οικουμενικό Πατριαρχείο.