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.
Fall of Ravenna
The Fall of Ravenna, capital of the Western Roman Empire, occurred in early September 476 after a minor confrontation between the Heruli under their King Odoacer and the remnants of the Western Roman Army in Italy. The Roman Empire had been in relative decline since the beginning of the barbarian invasions and Rome, the symbolical heart and largest city of the Western Empire, was sacked in 410 by the Visigoths and in 455 by the Vandals. By 476 the Roman Emperor was little more than a warlord having very little de facto control of any territory outside of Italy. The last Roman emperor, Romulus Augustulus, was not even recognized as a legitimate ruler outside of Italy; the Eastern Roman Empire recognized Julius Nepos as the true Western Roman Emperor.