This is a list of the Emperors of the late Eastern Roman Empire, called Byzantine by modern historians. This list does not include many of the emperors that ruled with someone else.
The title of all Emperors before Heraclius was Augustus, but other titles such as Dominus were also used. After Heraclius, the title was changed to the Greek Basileus. This title used to mean "king", "sovereign" but was now used in place of Augustus.
This list begins with Constantine I the Great, the first Christian emperor reigning from Constantinople.
At around this time the emperors began using the title Βασιλευς Βασιλεων Βασιλευων Βασιλευσιν, that is, Emperor of Emperors, ruling over those who rule.
In 1453 Mehmed II overthrew the Byzantine Empire and claimed the title of Kaisar; his successors continued this claim. See Ottomans for the complete list of Ottoman sultans.