From Smith's Dictionary of Greek and Roman Biography and Mythology

ANTENOR

a Trojan, a son of Aesyetes and Cleomestra, and husband of Theano, by whom he had many children. According to the Homeric account, he was one of the wisest among the elders at Troy, and received Menelaus and Odysseus into his house when they came to Troy as ambassadors. He also advised his fellow-citizens to restore Helen to Menelaus.

This is the substance of all that is said about him in the Homeric poems; but the suggestion contained therein, that Anterior entertained a friendly disposition towards the Greeks, has been seized upon and exaggerated by later writers.

Before the Trojan war, he is said to have been sent by Priam to Greece to claim the surrender of Hesione, who had been carried off by the Greeks; but this mission was not followed by any favourable result.

When Menelaus and Odysseus came to Troy, they would have been killed by the sons of Priam, had it not been for the protection which Antenor afforded them.

Just before the taking of Troy his friendship for the Greeks assumes the character of treachery towards his own country; for when sent to Agamemnon to negotiate peace, he devised with him and Odysseus a plan of delivering the city, and even the palladium, into their hands. When Troy was plundered, the skin of a panther was hung up at the door of Antenor's house, as a sign for the Greeks not to commit any outrage upon it.

His history after this event is related differently. Dictys states, that he founded a new kingdom at Troy upon and out of the remnants of the old one and according to others, he embarked with Menelaus and Helen, was carried to Libya, and settled at Gyrene or he went with the Heneti to Thrace, and thence to the western coast of the Adriatic, where the foundation of several towns is ascribed to him.

Antenor with his family and his house, on which the panther's skin was seen, was painted in the Lesche at Delphi.