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.
History of Western civilization before AD 500
The slow decline of the Western Empire occurred over a period of roughly three centuries, culminating in 476, when Romulus Augustus, the last Emperor of the Western Roman Empire, was deposed by Odoacer, a Germanic chieftain. Some modern historians question the significance of this date, and not simply because Julius Nepos, the legitimate emperor recognized by the East Roman Empire, continued to live in Salona, Dalmatia, until he was assassinated in 480. More importantly, the Ostrogoths who succeeded considered themselves upholders of the direct line of Roman traditions and, as the historian Edward Gibbon noted, the Eastern Roman Empire continued until the Fall of Constantinople on May 29, 1453.