Thoas (Θώας), son of Andraimon, was one of the heroes who fought for the Greeks in the Trojan War. He was a former suitor of Helen of Troy and led a group of forty ships for the Aetolians, one of the larger contingents. In the Iliad it states that he received his lordship because the previous dynasty of Oineus and Meleagros had perished, so the power to rule was bestowed on him. He was one of the nine volunteers to fight Hector in one on one combat, but lost to the drawing of lots to Telamonian Aias.

In the Iliad Poseidon impersonates Thoas to rally Idomeneus so that he will prevent Hector, who had just killed the sea god's grandson, and his forces from routing the Argives. Later Thoas advises the Greeks to retreat when Hector has broken through to the ships and the Trojan advance is pressing hard on them. He suggests this to prevent further disorder among the Greek forces. This suggestion led to the escape of some of them, who would otherwise have perished in the Trojans' imminent attack. He was one of the more prominent younger chiefs in the Iliad. In the Aeneid, Aeneas names Thoas as one of those Greeks hidden within the Trojan Horse (2.311).