The Palaiologos dynasty was the last imperial dynasty of the Byzantine Empire and one of the empire's longest ruling dynasties, ruling the empire from 1259/1261 to its fall in 1453.
As the Byzantine Empire collapsed over the course of the 14th and 15th centuries due to internal strife and the aggressive expansion of the Ottoman Empire, many Byzantine nobles fled their crumbling empire, travelling to Western Europe.
With the Fall of Constantinople in 1453 and the fall of the Despotate of the Morea, a Byzantine province, in 1460, the Palaiologoi were dispossessed.
In November 1460, the highest-profile Byzantine exile of them all, Thomas Palaiologos, younger brother of the final emperor Constantine XI, arrived in Rome, hoping to convince Pope Pius II to call for a crusade so that the empire could be restored.

Despite the hopes of Thomas, no crusade would ever be called again and Constantinople remained in Turkish hands.
He died in Rome and was survived by at least four children; Helena, Zoe, Andreas and Manuel.
His daughters had many descendants, but none carried the Palaiologos name, and while the elder son Andreas is most often presumed to have been childless, Manuel had two children; John and another Andreas, who converted to Islam.
John died young but Andreas lived longer, though is not believed to have had any children of his own.
With his death at some point in the 16th century, the imperial line of the Palaiologoi would thus have been rendered extinct.

This did little to stop individuals in various parts of Europe from claiming descent from the old imperial dynasty.
The family name Palaiologos had been relatively widespread in the Byzantine Empire, and the family had been quite extensive before a branch of it acceded to the imperial throne.
Many of the non-imperial Byzantine Palaiologoi were part of the nobility and served as generals or powerful landowners.
Many Byzantine refugees, though unrelated to the emperors, legitimately bore the name Palaiologos due to the extensive nature of the family.
Because the name could lend whoever bore it prestige (as well as possible monetary support), many refugees fabricated closer links to the imperial dynasty and were because of this welcomed at courts in Western Europe since many Western rulers were conscious of their failure to prevent Byzantium's fall.
It would have helped that many in Western Europe would have been unaware of the intricacies of Byzantine naming customs; to Western Europeans, the name Palaiologos meant the imperial dynasty.
The Palaiologos dynasty was the last imperial dynasty of the Byzantine Empire and one of the empire's longest ruling dynasties, ruling the empire from 1259/1261 to its fall in 1453. As the Byzantine Empire collapsed over the course of the 14th and 15th centuries due to internal strife and the aggressive expansion of the Ottoman Empire, many Byzantine nobles fled their crumbling empire, travelling to Western Europe. With the Fall of Constantinople in 1453 and the fall of the Despotate of the Morea, a Byzantine province, in 1460, the Palaiologoi were dispossessed. In November 1460, the highest-profile Byzantine exile of them all, Thomas Palaiologos, younger brother of the final emperor Constantine XI, arrived in Rome, hoping to convince Pope Pius II to call for a crusade so that the empire could be restored. 
Despite the hopes of Thomas, no crusade would ever be called again and Constantinople remained in Turkish hands. He died in Rome and was survived by at least four children; Helena, Zoe, Andreas and Manuel. His daughters had many descendants, but none carried the Palaiologos name, and while the elder son Andreas is most often presumed to have been childless, Manuel had two children; John and another Andreas, who converted to Islam. John died young but Andreas lived longer, though is not believed to have had any children of his own. With his death at some point in the 16th century, the imperial line of the Palaiologoi would thus have been rendered extinct.
This did little to stop individuals in various parts of Europe from claiming descent from the old imperial dynasty. The family name Palaiologos had been relatively widespread in the Byzantine Empire, and the family had been quite extensive before a branch of it acceded to the imperial throne. Many of the non-imperial Byzantine Palaiologoi were part of the nobility and served as generals or powerful landowners. Many Byzantine refugees, though unrelated to the emperors, legitimately bore the name Palaiologos due to the extensive nature of the family. Because the name could lend whoever bore it prestige (as well as possible monetary support), many refugees fabricated closer links to the imperial dynasty and were because of this welcomed at courts in Western Europe since many Western rulers were conscious of their failure to prevent Byzantium's fall. It would have helped that many in Western Europe would have been unaware of the intricacies of Byzantine naming customs; to Western Europeans, the name Palaiologos meant the imperial dynasty.
Paleologus of Pesaro