The Third Macedonian War (171168 BC) was a war fought between the Roman Republic and King Perseus of Macedon. In 179 BC, King Philip V of Macedon died and was succeeded by his ambitious son Perseus. He was anti-Roman and stirred anti-Roman feelings around Macedonia. Tensions escalated and Rome declared war on Macedon.

Most of the war was fought in Macedon as well as neighbouring Thessaly, where the Roman troops were stationed. After an inconclusive battle at Callinicus in 171 BC, and several more years of campaigning, Rome decisively defeated the Macedonian forces at the Battle of Pydna in 168 BC, bringing the war to a close.Rome's victory ended the Antigonid dynasty and brought an effective end to the independence of the Hellenistic kingdom of Macedon, although formal annexation was still some years away. The kingdom was divided into four client republics, each subservient to Rome. Roman prestige and authority in Greece was greatly increased as a result.

The Battle of Pydna took place in 168 BC between Rome and Macedon during the Third Macedonian War. The battle saw the further ascendancy of Rome in the Hellenistic world and the end of the Antigonid line of kings, whose power traced back to Alexander the Great. The battle is also considered to be a victory of the Roman legion's manipular system's flexibility over the Macedonian phalanx's rigidity.