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.
Prince-elector
From the 13th century onwards, the Prince-Electors had the privilege of electing the King of the Romans, who would be crowned by the Pope as Holy Roman Emperor. Charles V was the last to be a crowned Emperor (elected 1519, crowned 1530); his successors were elected Emperors directly by the electoral college, each being titled "Elected Emperor of the Romans" (; ). In practice, every emperor from 1440 onwards (except for Charles VII and Francis I) came from the Austrian House of Habsburg, and the Electors merely ratified the Habsburg succession.