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.
Julius Nepos
Julius Nepos (Latin: "Flavius Julius Nepos Augustus"; 430480) was Western Roman Emperor "de facto" from 474 to 475 and "de jure" until his death in 480. He was also the ruler of Roman Dalmatia from 468 to 480. Some historians consider Nepos to be the last Western Roman Emperor, while others consider the western line to have ended with Romulus Augustulus in 476. In contrast, the Eastern Roman Empire and its line of emperors survived this period of history essentially intact.