The Palaiologos (pl. Palaiologoi; Greek: Παλαιολόγος, -οι), also romanized as Palaeologus or Palaeologue, was the name of a Byzantine family, which rose to nobility and ultimately produced the last ruling dynasty of the Roman Empire.

Founded by the 11th-century general Nikephoros Palaiologos and his son George, the family rose to the highest aristocratic circles through its marriage into the Doukas and Komnenos dynasties. After the Fourth Crusade, members of the family fled to the neighbouring Empire of Nicaea, where Michael VIII Palaiologos became co-emperor in 1259, recaptured Constantinople and was crowned sole emperor of the Roman 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 Roman 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 descendants of the Palaiologoi of Montferrat.

The Palaiologos bloodline would also survive through the Anemids of Nicaea, who would eventually rise against their Ottoman masters and afterwards would found both the Kingdom of Nicaea and the Imperial State of Constantinople, before eventually establishing themselves as Kings of Greece, and finally restoring the Roman Empire.