Celtic chieftain who, when another tribe had created chaos in Macedonia by killing its king, led his tribe on a plundering expedition through Macedonia into Greece (autumn 279 BC). Held up at the pass of Thermopylae, he drew off the Aetolian contingent by sending a detachment into Aetolia, then outflanked the Greeks by the route the Persians had taken in 480. He pushed on to wealthy Delphi, but his forces were defeated, mainly by an Aetolian army (with Apollo's help, it was believed), and he was wounded. Withdrawing northward, Brennus saw most of his army killed, and he committed suicide.

Gallic chieftain who led an unsuccessful invasion of Greece in the autumn of 279. He advanced through Macedonia to Greece shortly after another group of Gauls had overrun Macedonia and killed its king. At the narrow pass of Thermopylae, on the east coast of central Greece, Brennus suffered heavy losses while trying to break through the Greek defense. Eventually he found a way around the pass—in much the same manner as the Persian invaders had done in 480 BC—but the Greeks escaped by sea. Brennus pushed on to Delphi, where he was wounded in battle; in the subsequent retreat northward few Gauls escaped. Brennus avoided capture by committing suicide.

chief of the Senones, who in 390 or 387 BC annihilated a Roman army, occupied and plundered Rome (ancient Rome), and exacted a heavy ransom before withdrawing. He is famous for his reputed saying, “Vae victis” (“Woe to the vanquished”). The name, which is not found in the best sources, may be invented.