wikipediaThomas Palaiologos or Palaeologus (Greek: Θωμᾶς Παλαιολόγος, romanized: Thomas Palaiologos; 1409 – 12 May 1465) was Despot in Morea from 1428 until the Ottoman conquest in 1460, though he continued to claim the title until his death in 1465. Thomas was the younger brother of the final Byzantine emperors John VIII and Constantine XI and also laid claim to the position of emperor following the Fall of Constantinople in 1453, during which Constantine died.
From 1453 to 1460, Thomas warred against his brother Demetrios over control of the Morea and over who was the rightful holder of the imperial title. This dispute came to an end when the Ottoman sultan Mehmed II, who had conquered Constantinople seven years prior, invaded the Morea. Thomas fled with his family to Italy and lived in exile in Rome from 1461. In Rome, Pope Pius II recognised him as the rightful "Emperor of Constantinople".
Thomas died in 1465 and despite his attempts and hopes, he had failed to garner enough support to kick-start a crusade that could have helped him claim Constantinople and restore the Byzantine Empire. His claims to the position of emperor and Despot of the Morea were maintained after his death by his oldest son Andreas.