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.
Ostrogothic Ravenna
In 476 the last emperor of the Western Roman Empire, Romulus Augustus, was forced to abdicate under invasions by Goths led by Odovacar. Upon the sacking of Rome by these Goths, Odovacar declared himself King of Italy and was able to conquer the peninsula as well as much of the "Dalmatian coast". Odovacar drew the ire of the imperial court at Constantinople as "a barbarian, a non-Roman, had deposed the Roman emperor in the original heartland of the empire. He had taken on the hated royal title and was getting ready to rule in the emperor’s place..." Odovacar, however, issued his coinage in the name of the emperor Nepos, whom Constantinople had never removed its recognition of when Romulus had assumed the imperial title therefore painting himself as merely overthrowing a previous usurper to the imperial throne.