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
In the Eastern Empire, sworn adherence to Christian orthodoxy became a prerequisite of Imperial accession – Anastasius I signed a document attesting his obedience to orthodox doctrine and practice. He is the last emperor known to be consecrated as "divus" on his death (AD 518). The title appears to have been abandoned on grounds of its spiritual impropriety but the consecration of Eastern emperors continued: they held power through divine ordinance and their rule was the manifestation of sacred power on earth. The "adventus" and the veneration of the Imperial image continued to provide analogies for devotional representations (Icons) of the heavenly hierarchy and the rituals of the Orthodox Church.