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.
Last Roman Emperor
Last Roman Emperor, Last World Emperor or Emperor of the Last Days is a figure of medieval European legend, which developed as an aspect of eschatology in the Catholic Church. The legend predicts that in the end times, a last emperor would appear on earth to reestablish the Holy Roman Empire and assume his function as biblical katechon who stalls the coming of the Antichrist. The legend first appears in the 7th-century apocalyptic text known as the "Apocalypse of Pseudo-Methodius"; that and the oracles of the Tiburtine Sibyl are its two most important sources. It developed over the centuries, becoming particularly prominent in the 15th century. The notion of Great Catholic Monarch is related to it, as is the notion of the Angelic Pope.