Palaeologus, a Byzantine family name which first appears in history about the middle of the 11th century, when George Palaeologus is mentioned among the prominent supporters of Nicephorus Botaniates, and afterwards as having helped to raise Alexius I. Comnenus to the throne in 1081; he is also noted for his brave defence of Durazzo against the Normans in that year. Michael Palaeologus, probably his son, was sent by Manuel II. Comnenus into Italy as ambassador to the court of Frederick I. in 1154; in the following year he took part in the campaign against William of Sicily, and died at Bari in 1155. A son or brother of Michael, named George, received from the emperor Manuel the title of Sebastos, and was entrusted with several important missions; it is uncertain whether he ought to be identified with the George Palaeologus who took part in the conspiracy which dethroned Isaac Angelus in favour of Alexius Angelus in 1195. Andronicus Palaeologus Comnenus was Great Domestic under Theodore Lascaris and John Vatatzes; his eldest son by Irene Palaeologina, Michael (q.v.), became the eighth emperor of that name in 1260, and was in turn followed by his son Andronicus II. (1282-1328). Michael, the son of Andronicus, and associated with him in the empire, died in 1320, but left a son, Andronicus III., who reigned from 1328 to 1341; John VI. (1355-1391), Manuel II. (1391-1425) and John VII. (1425-1448)1448) then followed in lineal succession; Constantine XI. or XII., the last emperor of the East (1448-1453), was the younger brother of John VII. Other brothers were Demetrius, prince of the Morea until 1460, and Thomas, prince of Achaia, who died at Rome in 1465. A daughter of Thomas, Zoe by name, married Ivan III. of Russia. A younger branch of the Palaeologi held the principality of Monferrat from 1305 to 1533, when it became extinct.
See Later Roman Empire, and articles on the separate rulers.
