The Palaeologus family was the last dynasty ruling the Byzantine Empire. After the Fourth Crusade members of the family escaped to Nicaea and eventually gained control of the empire-in-exile there. Michael VIII Palaeologus became emperor in 1259 and recaptured Constantinople in 1261. Michael's descendents ruled until the fall of Constantinople in 1453, the longest-lived dynasty in Byzantine history. The family motto was Basileus Basileon, Basileuon Basileuonton ("King of Kings, Ruling Over Those Who Rule").

Under the rule of the Palaeologi, the fragmented empire still claimed descent from the Roman Empire, but began to focus more on the empire's Greek character, as it no longer ruled an ethnically diverse state. The word "Hellene" began to be used again to describe themselves, after having been a synonym for "pagan" for many centuries. The dynasty was a patron of literature and the arts; among others, George Gemistos Plethon came to prominence. The hesychasm controversy also took place during the rule of the Palaelogan dynasty.

At this time the Peloponnese was the largest and wealthiest part of the empire, and was ruled as a Despotate by the Palaeologus family, often two or three brothers simultaneously. Although they often squabbled amongst themselves they were fiercely loyal to the emperor in Constantinople, while their land was surrounded by hostile Venetians and Turks. The capital of the despotate was Mystras, a large fortress built by the Palaeologi near Sparta.

The Palaeologi frequently attempted to reunite the Eastern Orthodox Church with the Roman Catholic Church, hoping this would lead the west to give them aid against the Turks. Every attempt at reunification was strongly opposed by the general population.

The family had connections throughout Europe. They married into the Bulgarian and Serbian royal families, as well as the noble families of Trebizond, Despotate of Epirus, Montferrat, and Muscovy.

The Palaeologan dynasty

Although the family was an old one (George Palaeologus was a friend of Alexius I Comnenus), the patriarch of the dynasty was Andronicus Palaeologus. His daughter Irene Palaeologina was the mother of Maria Cantacuzenus, who married both Constantine Tikh and Ivailo of Bulgaria. His son was the emperor Michael VIII.

Michael VIII was the father of Constantine, who in turn fathered John, who became the father-in-law of Stefan Decansky of Serbia. Michael's daughter Irene married Ivan Asen III of Bulgaria , and another daughter, Eudocia, married John II Comnenus of Trebizond. His son was Andronicus II Palaeologus.

Andronicus II married firstly Anna of Hungary and fathered Michael Palaeologus, sometimes numbered the ninth. His son, the grandson of Andronicus II, was Andronicus III Palaeologus. Michael's daughter Thedora married both Theodore Svetoslav and Michael Shishman , rulers of Bulgaria. By his second wife, Yolanda of Montferrat, Andronicus II had Simonis, later the wife of Stefan Milutin of Serbia.

Andronicus III was the father of John V Palaeologus. John V was the father, with Helena, a daughter of John VI Cantacuzenus, of Andronicus IV Palaeologus, who was himself the father of John VII Palaeologus. John V also fathered Manuel II Palaeologus.

Manuel II was the father of John VIII Palaeologus, the last Byzantine emperor, Constantine XI Palaeologus, and the despots of Morea Thomas and Demetrius Palaeologus. Thomas' daughter Zoe married Ivan III of Russia and was renamed Sophia.