This is a list of the Emperors of the East Roman or Byzantine Empire. This list does not include numerous co-emperors who never attained sole or senior status as rulers, nor the various usurpers or rebels who claimed the imperial title (on whom see List of Byzantine usurpers).

This list begins with Constantine the Great, the first Christian Roman Emperor, who founded Constantinople, and who was regarded by the later Byzantine Emperors as the model ruler. Diocletian before him is sometimes considered the first "Byzantine" Emperor in a political sense, as he replaced the republican trappings of the office with a straightforward autocracy, marking the transition from the Principate to the absolutist Dominate, a more typically oriental and Hellenistic form of monarchy that would characterize the Empire. It was under Constantine however that the major characteristics of the Byzantine state emerged: a Roman polity centered at Constantinople and culturally dominated by the Greek East, with Christianity as the state religion.

All Byzantine Emperors regarded themselves as Roman Emperors, the term "Byzantine" being coined firstly by Western historiography much later, in the 16th century. Although the Pope of Rome and the Germanic rulers of the West recognized the Eastern Empire's claim to the Roman legacy after the fall of the Western Roman Empire, on 25 December 800, Pope Leo III crowned King of Franks Charlemagne as the Roman Emperor (which eventually led to the formation of the Holy Roman Empire) due to uneasy relations with the Orthodox East, an act which was much resented by the Byzantines. This happened after the coronation of Empress Irene, who, as a woman, was not recognized by the Pope to have a right to the throne.