Constantine I (? – 9 August 677) was the

patriarch of Constantinople The ecumenical patriarch ( el, Οἰκουμενικός Πατριάρχης, translit=Oikoumenikós Patriárchēs) is the archbishop of Constantinople (Istanbul), New Rome and '' primus inter pares'' (first among equals) among the heads of th ...

from 675 to 677. He is listed as a saint, feast day July 29, on Wikipedia Eastern Orthodox Litúrgics. He was preceded by

John V of Constantinople John V (? – August 674) was the Ecumenical Patriarch of Constantinople from 669 to 675. He had ecumenically been proceeded by Thomas II of Constantinople. It was during his patriarchate time that the distressing first Siege of Constantinople ( ...

. He was succeeded by

Theodore I of Constantinople Theodore I (? – 28 January 687) was the Ecumenical Patriarch of Constantinople from 677 to 679. He had been preceded by Constantine I of Constantinople. During this cataclysmic period, the Byzantine military overcame the Arab incursion again ...

References

7th-century patriarchs of Constantinople {{Bishop-stub