Editing Emperor (section)

===Byzantine period===
{{Main|Byzantine Emperor}}

====Before the 4th Crusade====
[[File:Sanvitale03.jpg|thumb|Under [[Justinian I]], reigning in the 6th century, parts of Italy were for a few decades (re)conquered from the [[Ostrogoths]]: thus, this famous [[mosaic]], featuring the Byzantine emperor in the center, can be admired at [[Ravenna]].]]
Historians generally refer to the continuing Roman Empire in the east as the [[Byzantine Empire]] after [[Byzantium]], the original name of the town that [[Constantine I]] would elevate to the Imperial capital as [[New Rome]] in AD 330. (The city is more commonly called [[Constantinople]] and is today named [[Istanbul]]). Although the empire was again subdivided and a co-emperor sent to Italy at the end of the fourth century, the office became unitary again only 95 years later at the request of the [[Roman Senate]] and following the death of [[Julius Nepos]], last Western Emperor. This change was a recognition of the reality that little remained of Imperial authority in the areas that had been the Western Empire, with even Rome and Italy itself now ruled by the essentially autonomous [[Odoacer]].

These Later Roman "Byzantine" emperors completed the transition from the idea of the emperor as a semi-republican official to the emperor as an [[absolute monarch]]. Of particular note was the translation of the Latin ''Imperator'' into the Greek ''[[Basileus]]'', after Emperor [[Heraclius]] changed the official language of the empire from Latin to Greek in AD 620. Basileus, a title which had long been used for [[Alexander the Great]] was already in common usage as the Greek word for the Roman emperor, but its definition and sense was "King" in Greek, essentially equivalent with the Latin ''Rex''. Byzantine period emperors also used the Greek word "autokrator", meaning "one who rules himself", or "monarch", which was traditionally used by Greek writers to translate the Latin ''[[Roman dictator|dictator]]''. Essentially, the Greek language did not incorporate the nuances of the Ancient Roman concepts that distinguished ''imperium'' from other forms of political power.

In general usage, the Byzantine imperial title evolved from simply "emperor" (''basileus'') to "emperor of the Romans" (''basileus tōn Rōmaiōn'') in the 9th century, to "emperor and autocrat of the Romans" (''basileus kai autokratōr tōn Rōmaiōn'') in the 10th.<ref>[[George Alexandrovič Ostrogorsky|George Ostrogorsky]], "Avtokrator i samodržac", ''Glas Srpske kraljevske akadamije'' CLXIV, Drugi razdred 84 (1935), 95–187.</ref> In fact, none of these (and other) additional epithets and titles had ever been completely discarded.

One important distinction between the post Constantine I (reigned AD 306–337) emperors and their pagan predecessors was [[cesaropapism]], the assertion that the emperor (or other head of state) is also the head of the Church. Although this principle was held by all emperors after Constantine, it met with increasing resistance and ultimately rejection by bishops in the west after the effective end of Imperial power there. This concept became a key element of the meaning of "emperor" in the Byzantine and Orthodox east, but went out of favor in the west with the rise of [[Roman Catholicism]].

The Byzantine Empire also produced three women who effectively governed the state: the Empress [[Irene (empress)|Irene]] and the Empresses [[Zoe Porphyrogenita|Zoe]] and [[Theodora (11th century)|Theodora]].

====Latin emperors====
{{Main|Latin Emperor}}
In 1204 Constantinople fell to the [[Republic of Venice|Venetians]] and the [[Franks]] in the [[Fourth Crusade]]. Following the tragedy of the horrific [[Siege of Constantinople|sacking]] of the city, the conquerors declared a new "Empire of Romania", known to historians as the [[Latin Empire of Constantinople]], installing [[Baldwin IX]], [[Count of Flanders]], as Emperor. However, Byzantine resistance to the new empire meant that it was in constant struggle to establish itself. Byzantine Emperor [[Michael VIII Palaiologos]] succeeded in recapturing Constantinople in 1261. The [[Principality of Achaea]], a vassal state the empire had created in [[Morea]] (Greece) intermittently continued to recognize the authority of the crusader emperors for another half century. Pretenders to the title continued among the European nobility until circa 1383.

====After the 4th Crusade====
With Constantinople occupied, claimants to the imperial succession styled themselves as emperor in the chief centers of resistance: The [[Laskaris|Laskarid]] dynasty in the [[Empire of Nicaea]], the [[Komnenos|Komnenid]] dynasty in the [[Empire of Trebizond]] and the [[Doukas|Doukid]] dynasty in the [[Despotate of Epirus]]. In 1248, Epirus recognized the Nicaean emperors, who subsequently recaptured Constantinople in 1261. The Trapezuntine emperor formally submitted in Constantinople in 1281,<ref>Nicol, Donald MacGillivray, ''The Last Centuries of Byzantium'', second edition (Cambridge: University Press, 1993), p. 74.</ref> but frequently flouted convention by styling themselves emperor back in Trebizond thereafter.