a ruler of the eastern Roman Empire.

Royal or imperial title before Alexander, and later used by Byzantine sovereigns from 630 onward.

Greek - King or Emperor

Originally king, it became the title of the chief arkhon with jurisdiction over state religious observances. The plural is basileis.

the Greek term for king, a title taken by many of the successors of Alexander the Great and by later Byzantine emperors.

basileis (Gr., "king"): the main title for the Eastern Roman Emperor, used in conjunction with the words "of the Romans," on seals as early as the seventh century. The title was used in conjunction with autokrator.