One version of a late Classical tale, relates that she was of such striking beauty that both Hercules and Achelous wanted to marry her and there was a contest to win her hand at marriage. Her father had already betrothed her to the fearsome river god Achelous, horned and bull-like. Deianira was not passive, however. "This Deianira drove a chariot and practiced the art of war", noted Apollodorus (Library and Epitome, book i, 8:1), but she wanted nothing to do with her suitor, who was able to take the form of a speckled serpent, a bull-headed man, or a bull. Robert Graves interpreted the association with war as a relationship with the pre-Olympian war goddess, Athene, who was an orgiastic bride in many local sacred marriages to kings who may have been sacrificed. Heracles, the greatest hero of the dawning Classical Olympian world of deities and men, had to defeat the river god to win her as his bride.
In another version of her tale, Deianira is instead the daughter of Dexamenus, king of Olenus. Heracles violates her and promises to come back and marry her. While he is away, the centaur Eurytion appears, demanding her as his wife. Her father, being afraid, agrees. Heracles appears in the nick of time and slays the centaur, claiming his bride.
The central story of Deianira, however, concerns the Tunic of Nessus. A wild centaur named Nessus attempted to kidnap Deianira as he was ferrying her across the river Euenos, but she was rescued by Heracles, who shot the centaur with a poisoned arrow. As he lay dying, Nessus lied to Deianira, telling her that a mixture of olive oil with the semen that he had dropped on the ground and his heart's blood would ensure that Heracles would never again be unfaithful.
Deianira believed his words and kept a little of the potion by her. Heracles fathered illegitimate children all across Greece. Then Heracles fell in love with Iole (also called Omphal). When she became uncertain if Heracles would remain true to her in his fashion, Deianira smeared some of the blood on Heracles' famous hide shirt. Heracles' servant, Lichas, brought him the shirt and he put it on. The centaur's toxic blood burned Heracles terribly, and eventually, he threw himself into a funeral pyre. In despair, Deianira committed suicide by hanging herself or with a sword.