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.
Near East
It has pleased western historians to write of a decline of the Ottoman Empire as though a stable and uncontested polity of that name once existed. The borders did expand and contract but they were always dynamic and always in "question" right from the beginning. The Ottoman Empire was created from the lands of the former eastern Roman Empire on the occasion of the latter's violent demise. The last Roman emperor died fighting hand-to-hand in the streets of his capital, Constantinople, overwhelmed by the Ottoman military, in May, 1453. The victors inherited his remaining territory in the Balkans.