This is a list of Byzantine Emperors.
Note: It is difficult to determine when exactly the Roman Empire ends and the Byzantine Empire begins; the Roman Empire was actually split into eastern and western halves for administrative purposes by Diocletian in 284. Candidates for the "first" Byzantine emperor include Constantine I (the first Christian emperor, who moved the capital to Constantinople), Valens (the Battle of Adrianople (378) is one of the traditional ways to mark the start of the medieval period), Arcadius (as Theodosius I is often considered the last emperor of a single Roman Empire), and Zeno I (as the last western emperor Romulus Augustus was deposed during his reign). Others date the beginning of the Empire even as late as Heraclius (who made Greek the official language), and numismatists note the monetary reforms of Anastasius I in 498, which used the Greek numbering system. Of course, the Byzantines themselves continued to think of their empire as Roman for over a millennium.
Amorian (Phrygian) Dynasty
Lascaran Dynasty (in exile as the Empire of Nicaea)
Palaeologan Dynasty (restored at Constantinople)
See also Roman Emperors, Roman Empire, Byzantine Empire, and List of Byzantine Empire-related topics.