Holy Roman Empire
The empire was dissolved on 6 August 1806, when the last Holy Roman Emperor Francis II (from 1804, Emperor Francis I of Austria) abdicated, following a military defeat by the French under Napoleon at Austerlitz (see Treaty of Pressburg). Napoleon reorganized much of the Empire into the Confederation of the Rhine, a French satellite. Francis' House of Habsburg-Lorraine survived the demise of the empire, continuing to reign as Emperors of Austria and Kings of Hungary until the Habsburg empire's final dissolution in 1918 in the aftermath of World War I.
Constantine XI Palaiologos
Constantine XI Dragases Palaiologos, Latinized as Palaeologus (, "Kōnstantinos XI Dragasēs Palaiologos"; 8 February 1405 – 29 May 1453) was the last reigning Roman and Byzantine Emperor, ruling as a member of the Palaiologos dynasty from 1449 to his death in battle at the fall of Constantinople in 1453.