Thomas Palaiologos in the context of "Constantine XI Palaiologos"

The prince of Achaea was the ruler of the Principality of Achaea, one of the crusader states founded in Greece in the aftermath of the Fourth Crusade (1202–1204). The principality witnessed various overlords during its more than two centuries of existence, initially, Achaea was a vassal state of the Kingdom of Thessalonica under Boniface I of house Montferrat, then of the Latin Empire of Constantinople under the houses of Flanders-Courtenay, which had supplanted the Byzantine Empire, and later of the Angevin Kingdom of Naples. During the Angevin period, the princes were often absent, represented in the Principality by their baillis, who governed in their name. After 1404 the principality became sovereign as the Genoese Centurione II Zaccaria bought from the Neapolitan crown the princely rights.

The principality was one of the longest-lasting of the Latin states in Greece, outliving the Latin Empire itself by 171 years. It did not come to an end until 1432, when the Byzantine prince Thomas Palaiologos inherited the last remnants of the Principality through marriage to the daughter of the last prince, Centurione Zaccaria. With the Principality gone, the title of Prince of Achaea became vacant. However, in 1453 during the great Morean revolt of 1453-1454, John Asen Zaccaria, son of Centurione revived the Principality. He was confirmed as Prince by the Kingdom of Naples, the historical overlords of the Principality since 1267 and by Venice, though in 1455 John was forced to exile.

Demetrios Palaiologos or Demetrius Palaeologus (Greek: Δημήτριος Παλαιολόγος, romanized: Dēmētrios Palaiologos; 1407–1470) was Despot of the Morea together with his brother Thomas from 1449 until the fall of the despotate in 1460. Demetrios and Thomas were sons of Byzantine Emperor Manuel II Palaiologos, and brothers of the final two emperors John VIII and Constantine XI. Demetrios had a complicated relationship with his brothers, whom he frequently quarrelled with, usually over the matter of Demetrios's wish to establish himself as the most senior of them and claim the imperial throne for himself.

In 1437, Demetrios accompanied his elder brother John VIII to the Council of Florence, the main objective of which was to unify the Roman Catholic and Eastern Orthodox churches so that Western Europe might be more inclined to lend military aid to the desperate Byzantine Empire. Even though Demetrios was staunchly against a union of the churches, he was brought along as John did not dare to leave him in the east without he himself being present. Demetrios attempted to claim the throne twice, first attempting to take it with Ottoman support in 1442 and then by hoping to be proclaimed emperor after John VIII's death in 1448. Both attempts failed and in 1449, Demetrios was proclaimed as Despot of the Morea by the new emperor, his brother Constantine XI.

The Morea revolt of 1453–1454 was a failed rebellion carried out against the rule of the brothers Thomas and Demetrios Palaiologos, rulers of the Byzantine Despotate of the Morea in the Peloponnese peninsula.

Andronikos Palaiologos or Andronicus Palaeologus (Greek: Ἀνδρόνικος Παλαιολόγος) was a Byzantine prince and the last Byzantine governor of Thessalonica with the title of despot (despotēs), from 1408 to 1423.

Andronikos Palaiologos was a son of the Byzantine Emperor Manuel II Palaiologos and his wife Helena Dragaš. His maternal grandfather was the Serb prince Constantine Dragaš. His brothers included emperors John VIII Palaiologos and Constantine XI Palaiologos, as well as Theodore II Palaiologos, Demetrios Palaiologos and Thomas Palaiologos, who ruled as despots in Morea.

Catherine Asenina Zaccaria or Catherine Palaiologina (Medieval Greek: Αἰκατερίνα Παλαιολογίνα; died 26 August 1462) was the daughter of the Prince of Achaea, Centurione II Zaccaria and a Byzantine lady hailing from the prestigious houses of Asen-Palaiologos and the house of Tzamblakon. In September 1429 she was betrothed to the Byzantine Despot of the Morea Thomas Palaiologos, and married him in January 1430 at Mystras.

Sphrantzes in his Short History mentions a Kydonides Tzamblakon next to Thomas Palaiologos, that he calls the most beloved uncle of his wife. In 1459, this man aroused Thomas in a war against his brother Demetrios Palaiologos. Kydonides Tzamblakon was married to a sister of Catherine's mother. In Kalavryta there survives a palace known in the region as "the palace of Palaiologina," that according to tradition, was given as a personal gift by Constantine Palaiologos to his sister-in-law Catherine, and as such, received its name from her.

The Ottoman conquest of the Morea occurred in two phases, in 1458 and 1460, and marked the end of the Despotate of the Morea, one of the last remnants of the Byzantine Empire, which had been extinguished in the Fall of Constantinople in 1453.

The Despotate of the Morea had been founded as an autonomous appanage ruled by members of the Byzantine imperial Palaiologos dynasty. During the 14th and 15th centuries, it was the scene of the last flourishing of Byzantine culture, but in the 1420s it was repeatedly attacked by Ottoman raiders under Turahan Bey, and was reduced to a tributary vassal by Sultan Murad II in 1446. From 1449, it was ruled by the brothers Demetrios Palaiologos and Thomas Palaiologos, who were engaged in a constant rivalry with one another: they divided the Morea peninsula among themselves, and neglected the payment of tribute to the Sultan. Having lost his patience with the quarreling brothers, and determined to avoid the Morea being used as a springboard for a Western crusade against him following his capture of Constantinople, Sultan Mehmed II invaded the peninsula in May 1458. While part of his forces besieged the Acrocorinth, the rest ravaged the peninsula. After the fall of the Acrocorinth, the two Palaiologoi brothers capitulated. Acrocorinth, Thomas' capital, Patras, and much of the northern part of the peninsula came under direct Ottoman rule; the Palaiologoi were left as tributary rulers in the southern half, which included the Despotate's capital, Mystras.