Slavs definitely.
Silly answer
The highest Church official was the Patriarch, who was considered superior to all the Archbishops and bishops. When the Byzantine empire still controlled all the areas of the Levant and North Africa there were other Patriarchs at Antioch, Jerusalem and Alexandria. As he was in the imperial capital at Constantipole he was considered the most important when they met in Council. After the Muslim invasions the other patriarchs have dwindled to unimportance. The current Patriarch has a very small congregation in Istanbul, after the Greeks were expelled at the end if the first world war. He is still considered the head of the Orthodox Church, though the patriarch in Moskva controls far more adherents.
The Byzantine Empire was an Orthodox Christian Theocracy and the Emperor of the Byzantine Empire had both secular authority as the leader of the Byzantine Empire and theological authority as the Vicegerent of Christ. However, the Emperor was not always involved in the day-to-day activities of the Church and that was led by the Patriarch of Constantinople, who still remains the head of Orthodox Christianity.
pope
The Hagia Sophia was the largest and most important Greek Orthodox Cathedral of the Byzantine Empire.
silk
The most important person was Justinian. He ruled most of the Western and eastern.
Byzantine
The Clergy
which ancient Indians leader was most important
Jefferson Davis was the President of the Confederacy while Robert E. Lee was its most important military leader
governer
All leaders of Russia were important.
there are 3 species of llama
Its tightly centralized rule under a powerful emperor. :)
my dikk Lol:D