(203?–120? bc), Greek historian, born in Megalopolis. He was one of the thousand noble Achaeans who, after the conquest of Macedonia in 168 bc, were sent to Rome as hostages. At Rome, Polybius was received into the home of the Roman general Lucius Aemilius Paullus (229?–160? bc) and became the tutor of his two sons, the younger of whom was adopted into the Scipio family, becoming known as Scipio Africanus the Younger. Scipio and Polybius became close friends. In 151 bc, after 16 years in Italy, the surviving Achaean exiles were permitted by the Roman Senate to return to Greece. Polybius, however, soon rejoined Scipio, followed him in his African campaign, and was present at the destruction of Carthage in 146 bc. The outbreak of the war between the Achaeans and the Romans called him again to Greece, where he was of the greatest service, through his influence with the Romans, in procuring favorable terms for the vanquished.

The latter part of his life was devoted to the composition of his great work, Universal History (40 vol.). His purpose was to show how and why all the civilized countries of the world fell under the dominion of Rome. The work covers the period between 220 and 146 bc, the year that Corinth fell. Although much of the greater part of the work has perished—only the first five books are fully preserved—the plan of the whole is fully known. As a historian Polybius tried not merely to present facts but to discover the causes of these facts and to draw from them lessons valuable for the future. His tone is frequently didactic, and the continuity of his narrative is often interrupted by digressions. His style is simple and clear. In the history of Greek literary style his work is significant for its employment of the so-called common dialect, a modified Attic, which came into use about 300 bc.