Who was the head of the Eastern Orthodox church originally appointed by Byzantine emperor?

The head of the Eastern Orthodox Church originally appointed by the Byzantine emperor is known as the Patriarch of Constantinople. Established as a prominent ecclesiastical leader, the Patriarch served not only as a spiritual authority but also had significant influence in state matters. The role has evolved over time, particularly following the Great Schism of 1054, which formalized the split between Eastern Orthodoxy and Roman Catholicism. Today, the Patriarch is viewed as a key figure in Eastern Orthodox Christianity, representing unity among the various Orthodox jurisdictions.