Constantius I of Constantinople

{{Short description|Ecumenical Patriarch of Constantinople from 1830 to 1834}}

{{Use dmy dates|date=January 2025}}

{{Infobox Patriarch

| name = Constantius I of Constantinople

| patriarch_of = Ecumenical Patriarch of Constantinople

| image = Konstantius I.jpg

| caption =

| enthroned = 6 July 1830

| ended = 18 August 1834

| province =

| diocese = Constantinople

| see = Ecumenical Patriarchate

| church = Church of Constantinople

| predecessor = Agathangelus of Constantinople

| successor = Constantius II of Constantinople

| birth_name =

| birth_date = 1770

| birth_place = Constantinople

| death_date = 5 January 1859

| death_place = Burgazada

| buried =

| religion = Eastern Orthodox Church

}}

Constantius I of Constantinople ({{langx|el|Κωνστάντιος}}; 1770 – 5 January 1859) was Ecumenical Patriarch of Constantinople during the period 1830–1834.

He was born in 1770 in Constantinople.{{Cite web |title=Πανδέκτης: Κωνστάντιος Α΄, πατριάρχης Κωνσταντινουπόλεως |url=http://pandektis.ekt.gr/dspace/handle/10442/57766 |access-date=31 December 2022 |website=pandektis.ekt.gr}} He studied in the Patriarchal School, in Iași and in Kiev. In 1805, he was elected Archbishop of Sinai, a position he held until he was elected Ecumenical Patriarch in 1830. He resigned in 1834 and devoted his life to studying and writing. He died on 5 January 1859.{{Cite web |language=el |date=25 July 2019 |title=Κατάλογος Οικουμενικών Πατριαρχών - Οικουμενικό Πατριαρχείο |url=https://ec-patr.org/oikoymeniko-patriarxeio/istoria/diatelesantes-patriarxes/ |access-date=31 December 2022}}