Roman emperor
The Western Roman Empire collapsed in the late 5th century. Romulus Augustulus is often considered to be the last emperor of the West after his forced abdication in 476, although Julius Nepos maintained a claim recognized by the Eastern Empire to the title until his death in 480. Following Nepos' death, the Eastern Emperor Zeno abolished the division of the position and proclaimed himself as the sole Emperor of a reunited Roman Empire. The Eastern imperial lineage continued to rule from Constantinople ("New Rome"); they continued to style themselves as Emperor of the Romans (later βασιλεύς Ῥωμαίων in Greek), but are often referred to in modern scholarship as Byzantine emperors. Constantine XI Palaiologos was the last Roman emperor in Constantinople, dying in the Fall of Constantinople to the Ottomans in 1453.
Imperial cult of ancient Rome
Constantine's nephew Julian, Rome's last non-Christian emperor, rejected the "Galilean madness" of his upbringing for a synthesis of neo-Platonism, Stoic asceticism and universal solar cult and actively fostered religious and cultural pluralism. His restored Augustan form of principate, with himself as "primus inter pares", ended with his death in 363, after which his reforms were reversed or abandoned. The Western emperor Gratian refused the office of "pontifex maximus" and, against the protests of the Senate, removed the altar of "Victoria" (Victory) from the Senate House and began the disestablishment of the Vestals. Theodosius I briefly re-united the Western and Eastern halves of the Empire, officially adopted Nicene Christianity as the Imperial religion and ended official support for all other creeds and cults. He refused to restore "Victoria" to the Senate House, extinguished Vesta's sacred fire and vacated her temple. Even so, he accepted address as a living divinity, comparable to Hercules and Jupiter, by his overwhelmingly pagan Senate. After his death the sundered Eastern and Western halves of Empire followed increasingly divergent paths: nevertheless both were Roman and both had emperors. Imperial ceremonial – notably the Imperial "adventus" or ceremony of arrival, which derived in greater part from the Triumph – was embedded within Roman culture, Church ceremony and the Gospels themselves.