| Honorific-Prefix: | His All Holiness |
| Constantius II | |
| Patriarch Of: | Ecumenical Patriarch of Constantinople |
| Enthroned: | 18 August 1834 |
| Ended: | 26 September 1835 |
| Diocese: | Constantinople |
| See: | Ecumenical Patriarchate |
| Church: | Church of Constantinople |
| Predecessor: | Constantius I |
| Successor: | Gregory VI |
| Birth Date: | 1789 |
| Death Date: | 1859 |
| Death Place: | Arnavutköy |
| Religion: | Eastern Orthodox Church |
| Occupation: | Ecumenical Patriarch |
Constantius II (Greek: Κωνστάντιος; 1789–1859) served as Ecumenical Patriarch of Constantinople during the period 1834–1835.
Before his election as Ecumenical Patriarch in 1834, he had been Metropolitan bishop of Veliko Tarnovo. He wasn't particularly educated, nor did he have administrative skills. So, the next year he had to resign. He retired to Arnavutköy on the Bosphorus, where he died in 1859. He was buried in the forecourt of the Holy Church of Asomatoi in Arnavutköy.