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.
Frederick III, Holy Roman Emperor
Frederick III (21 September 1415 – 19 August 1493) was Holy Roman Emperor from 1452 until his death. He was the first emperor of the House of Habsburg, and the third member of the House of Habsburg to be elected King of Germany after Rudolph I of Germany and Albert I in the 13th century. He was the penultimate emperor to be crowned by the Pope, and the last to be crowned in Rome.