Pyrrhus of Epirus (319–272 bce), son of Aeacides and Phthia, most famous of the Molossian kings (see molossi), chief architect of a large, powerful, and Hellenized Epirote state (see hellenism; epirus), and builder of the great theatre at Dodona. After reigning as a minor from 307/6 to 303/2, he was driven out and followed for a time the fortunes of Demetrius (4) Poliorcetes. With the support of Ptolemy (1) I, whose stepdaughter Antigone he married, and of Agathocles (1) of Syracuse, he became joint king with Neoptolemus, whom he soon removed. Early in his reign he annexed and retained southern Illyria (see illyrii), probably as far as Epidamnus. He tried to emancipate Epirus from Macedonia. By intervening in a dynastic quarrel in Macedonia Pyrrhus obtained the frontier provinces of Parauaea and Tymphaea, together with Ambracia, Amphilochia (see amphilochi), and Acarnania. On the death of Antigone he acquired Corcyra and Leucas as the dowry of his new wife, Lanassa daughter of Agathocles, and made alliances with the Dardanian chief Bardylis (see dardani) and the Paeonian king Audoleon, whose daughters he also married. Conflict with Demetrius (from 291), now king of Macedon, saw substantial gains in Thessaly and Macedonia, but these were largely lost later to Lysimachus (284).

Appealed to by the Tarentines (as his uncle Alexander (6) of Epirus and the Spartans Archidamus III and Cleonymus before him), Pyrrhus went to assist them in their Hellenic struggle against Rome. With a force of 25,000 infantry, 3,000 horse, and 20 elephants he defeated the Romans at Heraclea (1) (280), though not without loss, and won the support of the Samnites, Lucanians, Bruttians (see samnium; lucania; bruttii), and Greek cities of the south. He marched towards Rome, but prolonged negotiations failed to secure peace. In 279 he defeated the Romans again, at Ausculum, but again with heavy losses. Late in the same year he received an appeal from Syracuse and in 278 sailed to Sicily, where he fought the Carthaginians, then allies of Rome, and Mamertines. In 276 he abandoned the campaign (perhaps by then a lost cause) and returned to Italy, whither he was urgently summoned by his allies in the south. After more losses (including eight elephants and his camp) in battle with the Romans at Malventum (renamed thereafter Beneventum) in 275, he returned to Epirus with less than a third of his original force. A garrison was left behind at Tarentum, signifying perhaps future intent, but the Italian manpower at Rome's disposal had triumphed decisively. Pyrrhus himself embarked upon a new attempt at Macedonia. Initial success and a brief time as king there in 274 gave way to unpopularity after he plundered the royal tombs at Aegae, and in 273 he marched into the Peloponnesus. Following a failed attack on Sparta he went to Argos (1), where in 272 he died, struck on the head by a tile thrown from the roof of a house; in the same year Tarentum fell to the Romans.