Gennadius I, patriarch of Constantinople

Gennadius of Constantinople was the patriarch of Constantinople from August 458 until his death. Gennadius is known to have been a learned writer who followed the School of Antioch of literal exegesis, although few writings have been left about him. He is commemorated in the Eastern Orthodox Church on 17 November but is not listed in the Roman Martyrology.

The ecumenical patriarch of Constantinople is the archbishop of Constantinople and primus inter pares among the heads of the several autocephalous churches that comprise the Eastern Orthodox Church. The ecumenical patriarch is regarded as the representative and spiritual leader of the Eastern Orthodox Christians worldwide. The term ecumenical in the title is a historical reference to the Ecumene, a Greek designation for the civilised world, i.e. the Roman Empire, and it stems from Canon 28 of the Council of Chalcedon.