(Ἀτταγῖνος), the son of Phrynon, one of the leading men in Thebes, betrayed Thebes to Xerxes on his invasion of Greece (Paus. 7.10.1), and took an active part in favour of the Persians. He invited Mardonius and fifty of the noblest Persians in his army to a splendid banquet at Thebes, shortly before the battle of Plataea, B. C. 479. After the battle, the Greeks marched against Thebes, and required Attaginus, with the other partisans of the Median party, to be delivered up to them. This was at first refused; but, after the city had been besieged for twenty days, his fellow-citizens determined to comply with the demands of the Greeks. Attaginus made his escape, but his family were handed over to Pausanias, who dismissed them without injury. (Hdt. 9.15, 86, 88; Athen. 4.148e.)