Eugenius I of Byzantium

{{Short description|Bishop of Byzantium from 240 to 265}}

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{{Infobox patriarch

| name = Eugenius I of Byzantium

| patriarch_of = Bishop of Byzantium

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| enthroned = {{Circa|240}}

| ended = {{Circa|265}}

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| predecessor = Castinus of Byzantium

| successor = Titus of Byzantium

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| death_date = {{Circa|265}}

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| religion = Early Christianity

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Eugenius I of Byzantium ({{langx|el|Ευγένιος Αʹ|}}; died {{circa|265}}) was the bishop of Byzantium from around 240 until his death in {{Circa|265}}.{{Cite web |title=Ευγένιος Αʹ |url=https://ec-patr.org/oikoymeniko-patriarxeio/istoria/diatelesantes-patriarxes/ |access-date=21 February 2024 |website=ec-patr.org |series=Κατάλογος Οικουμενικών Πατριαρχών [List of Ecumenical Patriarchs] |date=25 July 2019 |publisher=Ecumenical Patriarch of Constantinople |language=el}}{{Cite book |last=Kiminas |first=Demetrius |url=https://books.google.com/books?id=QLWqXrW2X-8C |title=The Ecumenical Patriarchate: A History of Its Metropolitanates with Annotated Hierarch Catalogs |publisher=Wildside Press |year=2009 |isbn=9781434458766 |pages=30–44 |access-date=21 February 2024}}[https://sourcebooks.fordham.edu/byzantium/texts/byzpatcp.asp Fordham University, History Department, Bishops/Patriarchs of Constantinople]