Polybius (204?–;122? B.C.), a Greek historian. Of the 40 books making up his history of Rome, only 5 complete books and fragments of others survive. The history extends from the Punic Wars to the destruction of Corinth, or from about 266 B.C. to 146 B.C. It is filled with moralizing and attempts a justification of Roman conquests. Nevertheless, it is valuable for its on-the-scene descriptions.

Polybius was born in Megalopolis. He was an officer in the Achaean League and was taken to Rome as a captive. There he enjoyed the patronage of the younger Scipio Africanus. He returned to Greece about 151 B.C., and later was the Achaean League's ambassador to Egypt.