Constantine Palaiologos was the last Emperor of Constantinople, the New Rome. He was killed defending his city against the Ottoman Turks in 1453. The Turkish conquest completed the transformation of the Christian Byzantine Empire into the Muslim Ottoman Empire. Constantine's death marked the end of an institution that traced its origins back to the reign of Constantine the Great in the fourth century, or indeed back to Augustus, the first Roman Emperor. For its ruler and people called themselves Romaioi or Romans, not Hellenes or Greeks. The last Constantine reigned as Emperor for not much more than four years. His dominions were restricted to the city and suburbs of Constantinople and a portion of Greece. He ruled them at the mercy of the Turks. But he was proudly conscious of the fact that so long as he held the Queen of Cities he was the one true Emperor of the Romans.

He was the eighth member of his family to inherit the title since his ancestor Michael Palaiologos had usurped the imperial throne in 1261. He is generally reckoned to have been the eleventh Emperor with the name of Constantine, although Edward Gibbon and others have found reasons for calling him Constantine XII. The facts of his career were recorded by Byzantine chroniclers who knew him and by later Greek historians. The circumstances of his death during the Turkish assault on Constantinople, one of the most dramatic events of the Christian Middle Ages, were described by numerous observers and reporters, Greek, Italian, Turkish and Slav; and the drama of the siege and capture of the city has been eloquently told in more recent years, notably by Sir Steven Runciman.