User blog:JonathanMarkoff/Byzantine Emperor (for my amusement)

The office of Emperor of the Roman Empire in the East (i.e., of the Byzantine Empire) was never formally created, but simply "spun off" from the leadership position of the original Roman Empire. In 330, Roman Emperor Constantine I moved his capital to Constantinople, the city formerly known as Byzantium, which remained the seat of power of the Eastern Empire after the schism with the Western subdivision. The Byzantine Emperors all claimed rulership of "the Romans" until Constantinople's fall to the Ottoman Empire in 1453 AD. The title of all Byzantine Emperors until the reign (610-641) of Herakleios, was officially "Augustus," although other titles such as Dominus were also used. Their names were preceded by Imperator Caesar and followed by Augustus. Following Herakleios the title commonly became the Greek Basileus (Βασιλεύς), which had formerly meant "king" but was then used in place of Augustus. Following the establishment of the rival Holy Roman Empire in Western Europe, the title "Autokrator" (Gr. Αὐτοκράτωρ) was increasingly used. In later centuries, the Emperor could be referred to by Western Christians as the "Emperor of the Greeks". Towards the end of the Empire, the standard imperial formula of the Byzantine ruler was "[Emperor's name] in Christ, Emperor and Autocrat of the Romans" (cf. Ῥωμαῖοι and Rûm).

Constantine XI Palaiologos was the last Christian Emperor of Constantinople, however the conquering Ottoman Emperors used "Caesar of the Romans" up until their Empire fell in 1922.

Harry Turtledove's fiction has made the following use of the office of the Byzantine Emperor.

Agent of Byzantium
Although the Empire was torn by civil war at the turn of the 7th century, it endured and consolidated its status as one of the leading powers in the world by the early 14th century. Some Emperors had more colorful personalities than others.

While the ill-fated Maurice was Emperor, Mouamet, a pagan merchant on the Empire's eastern fringes, converted to Christianity, and later became a bishop and writer of hymns. While Saint Mouamet remained a popular cultural touchstone down the ages, it is doubtful that his conversion had any profound impact on history.

"Islands in the Sea"
Leo III was the last Emperor of the Byzantine Empire, and was killed during the fall of Constantinople to the Caliphate in 718. When rival Christian and Muslim delegations courted the spiritual leanings of the Bulgar nation in 769, one member of the former was Niketas, grandson of Leo. His fellow diplomats speculated that had the siege gone differently, Niketas might now be Emperor.

Other Emperors
The novel Justinian is set in OTL and is partly a fictional autobiography of Justinian II, recounting his rise and fall. In addition to Justinian's POV role, Emperors Constantine IV and Leo III also appear directly, while Constantine V is referenced as the reigning Emperor in the frame story. Several Emperors from previous centuries are the subject of extensive posthumous references.

Alexios I is the POV character in "Two Thieves," a science fiction story set in the Riverworld shared universe. Centuries after his OTL death, Alexios is resurrected by aliens and becomes the monarch of New Constantinople, a city-state on the series' titular planet.

Constantine XI, the final Emperor in OTL, is a POV character in "The Emperor's Return," a story with both science fiction and fantasy elements. It depicts Constantine's last stand during the OTL fall of Constantinople, before a supernatural event transfers the story to a hypothetical future.