The second wife of Heracles and the daughter of Oeneus, the king of Calydon.
Heracles won her by a wrestling match with the river god Achelous, who also desired to marry her.
While dining with Oeneus, Heracles accidentally killed a boy, who was washing Heracles' hands. This was an accident, and Oeneus forgave him. Still, Heracles exiled himself as punishment. While travelling from Calydon, he met the Centaur Nessos, who was acting as a ferryman across a certain river. Heracles crossed on his own, but paid Nessos to take Deianeira across. While crossing, Nessos tried to rape Deianeira. Heracles heard her cries, and shot the Centaur from the shore. While Nessos was dying, he gave to Deianeira a potion of his blood and semen, which he claimed would insure that Heracles love her.
After many more battles, Heracles returned to Oichalia, to seek his revenge upon Eurytos, who had refused to marry his daugther Iole. He attacked the town, killed Eurytos, and took Iole as his concubine. Deianeira became jealous of this new concubine. Remembering the words of Nessos, she took out the potion, thinking it to be a love potion, and spread it on Heracles' tunic.
When Heracles put on the tunic, he was poisoned. He had a pyre made, upon which he was burned. When Deianeira found out what had happened, she hung herself.