Romulus Augustulus
Flavius Romulus Augustus (c. AD 460 – after AD 476; possibly still alive as late as AD 507), known derisively and historiographically as Romulus Augustulus, was the Roman emperor who ruled the Western Roman Empire from 31 October 475 until 4 September 476. He is often described as the "last Western Roman emperor", though some historians consider this to be Julius Nepos. His deposition by Odoacer traditionally marks the end of the Roman Empire in the West, the end of Ancient Rome, and the beginning of the Middle Ages in Western Europe.
Western Roman Empire
Charlemagne, and the subsequent Holy Roman Emperors, were not, and did not claim to be, rulers of a restored Western Roman Empire. Pope Leo III and contemporary historians were fully aware of that the notion of a separate Western court had been abolished over three centuries prior and considered the Roman Empire to be "one and indivisible". The ruler of the Roman Empire at the time of Charlemagne's coronation was Irene, the mother of emperor Constantine VI who she had deposed. Leo III considered Irene to be a usurper and illegitimate to rule due to her gender and as such considered the imperial throne to be vacant. Thus, Charlemagne was not crowned as the ruler of the Western Roman Empire and successor to Romulus Augustulus, but rather as the successor of Constantine VI and as sole Roman Emperor. Irene was deposed and replaced by Emperor Nikephoros soon after, and the Eastern Empire refused to recognize the Imperial title of Charlemagne. Following several wars in the 810s Emperor Michael I Rangabe eventually recognized Charlemagne as an "Emperor", but as the slightly humiliating "Emperor of the Franks" rather than "Roman Emperor", a title he reserved for himself. For centuries to come, the "revived" Western court and the Eastern court, in direct succession to the Roman Emperors of old, would make competing claims to be rulers of the whole Roman Empire. With the Eastern Empire terming the Holy Roman Empire as an "Empire of the Franks", the term "Empire of the Greeks" was popularized in the Frankish court as a way to refer to the Empire centered in Constantinople.