In 1204 the knights of the Fourth Crusade set up a Crusader state known as the Latin Empire, or Romania, based in Constantinople, after sacking that city. They intended it to be a Roman Catholic successor to the Byzantine Empire. Baldwin IX, Count of Flanders, was crowned the first emperor on May 16, 1204.


The Latin title of the emperor was Imperator Romaniae, or "Emperor of Romania". This name had nothing to do with the modern country by that name; rather, it is the Latin form of the title of the Byzantine Emperor, whom the Latin Emperor hoped to replace. The Byzantine Empire was never called that at the time, and the Byzantine Emperor's title was Basileus Rōmaiōn, or "Emperor of the Romans". This had the curious effect of creating three Roman Empires in Europe at the same time, the others being the Holy Roman Empire and the remnant of the Byzantine Empire.

The Latin Empire laid claim to all of the lands controlled by the Byzantine Empire at the time Constantinople was conquered, and did exert control over areas of Greece (the Crusader States: the Kingdom of Thessalonica, the Principality of Achaea, and the Duchy of Athens). However, much of the territory remained in the hands of rival states led by aristocrats of the former empire, such as the Byzantine Greek successor states of Epirus, Nicaea, and Trebizond. Although the relatives of Baldwin, Count of Flanders struggled for many years for their domain, the Latin Empire ended on July 25, 1261 when Michael VIII Palaeologus recaptured Constantinople, deposing the last Latin Emperor, Baldwin II.

For about a century thereafter, the heirs of Baldwin II continued to use the title of Emperor of Constantinople, and were seen as the overlords of the various remaining Latin states in the Aegean. They exercised effective authority in Greece only when actually ruling as princes of Achaea, as in 1333–1383. Although they are generally regarded as titular emperors, the continued existence of Latin states in the Aegean that recognized them as their suzerains makes the term a misnomer; a more accurate description would be emperors in exile.