Palaiologos (Greek: Παλαιολόγος, pronounced [paleoˈloɣos], in plural Παλαιολόγοι, [paleoˈloʝi]), often Latinized as Palaeologus, was a Byzantine Greek noble family, which produced the last ruling dynasty of the Byzantine Empire. After the Fourth Crusade, members of the family fled to the neighboring Empire of Nicaea, where Michael VIII Palaiologos became co-emperor in 1259, recaptured Constantinople and was crowned sole emperor of the Byzantine Empire in 1261. His descendants ruled the empire until the Fall of Constantinople at the hands of the Ottoman Turks on May 29, 1453, becoming the longest-lived dynasty in Byzantine history; some continued to be prominent in Ottoman society long afterwards. A branch of the Palaiologos became the feudal lords of Montferrat, Italy. This inheritance was eventually incorporated by marriage to the Gonzaga family, rulers of the Duchy of Mantua, who are descendents of the Palaiologoi of Montferrat.

The Palaiologoi were originally petty lords from Macedonia, but their earliest generations are unknown. The family is first attested in the 11th century, with Nikephoros Palaiologos, general under Michael VII Doukas. His son George Palaiologos was a friend of Alexios I Komnenos and brother-in-law to Alexios' wife Irene Doukaina. He commanded the garrison of Dyrrhachium during the Battle of Dyrrhachium against Robert Guiscard, the Norman Duke of Apulia and Calabria in 1081.

Constantine XI Palaiologos, Latinized as Palaeologus (Greek: Κωνσταντῖνος ΙΑ' Δραγάσης Παλαιολόγος (Serbian: Константин Палеолог Драгаш), Kōnstantinos XI Dragasēs Palaiologos; 8 February 1404 – 29 May 1453) was the last reigning Byzantine Emperor. from 1449 to his death as member of the Palaiologos dynasty. After his death in battle during the fall of Constantinople, he became a legendary figure in Greek folklore as the "Marble Emperor" who would awaken and recover the Empire and Constantinople from the Turks. His death marked the final end of the Roman Empire, which had continued in the East for 977 years after the fall of the Western Roman Empire.

Constantine was born in Constantinople as the eighth of ten children to Manuel II Palaiologos and Serbian Helena Dragaš, the daughter of the Serbian prince Constantine Dragaš. He spent most of his childhood in Constantinople under the supervision of his parents. During the absence of his older brother in Italy, Constantine was regent in Constantinople from 1437–1440.

Manuel Palaiologos (or Palaeologus) (1455–1512) was the youngest child of Thomas Palaiologos and Catherine Zaccharia. He was brother of the de jure Byzantine Emperor Andrew Palaiologos, Zoe Palaiologina, Grand Duchess of Moscovy and Helena Palaiologina, wife of Despot Lazar Branković of Serbia. He was also a nephew of the Emperors John VIII Palaiologos and Constantine XI.

Born after the Fall of Constantinople (May 29, 1453) he spent his early childhood in the Morea (modern Peloponnese) till fleeing with his family in 1460 firstly to Corfu then Rome where his father was recognised as Byzantine Emperor. Sources claim after the death of Thomas Palaiologos in 1465, his children were placed under the guardianship of the renowned scholar, Johannes Bessarion.

Little is known about his life except he returned to Constantinople during the reign of Bayezid II and exchanged his rights to the Byzantine throne for a comfortable pension. Here he spent his life in luxury and pleasure, fathering two sons, an enigmatic John (Ioannes) and Andrew (Andreas) with a Turkish^{[citation needed]} woman (possibly a slave in his household). He died in 1512.