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.
Orestes (5th century general)
In 475, Orestes was appointed "magister militum" and "patricius" by Western Roman Emperor Julius Nepos. This proved to be a mistake on the part of Nepos. By August 28, 475, Orestes, at the head of the "foederati" levies, managed to take control of the government in Ravenna, which had been the de facto capital of the Western Roman Empire since 402. Julius Nepos fled without a fight to Dalmatia, where he would continue to reign until his assassination in 480. With the emperor far away, Orestes elevated his son Romulus to the rank of "Augustus", so that the last Western Roman emperor is known as Romulus Augustulus meaning "little Augustus" as the emperor was only a 15-year-old boy at the time he became emperor in 475.