This ancient constellation represents Hercules, son of Zeus and Alcmene, Amphitryon's wife. He became immortal when he succeeded in sucking milk from the breast of sleeping Hera, with the complicity of the same Zeus and Hermes. In that occasion there was the creation of the Milky-Way: when she woke up, Hera removed the child, but the milk splashed the sky, leaving the notorious "trace". This episode, together with the anger for the treason, shows the reason of Hera's hate towards Hercules and, being unable in killing him, she will try to make his life impossible. Infact, the hero, under her wicked influence, killed his sons and then went, repented, to Delphy's Oracle, to know how to delete his fault. Then he knew that he had to go to the King Euristeus in Mycenae, to serve him . So King Euristeus assigned to Hercules ten impossible tasks that, together with other two, became the legendary Twelve Labours. We remember the most famous ones.

In the first labour, Hercules killed the terrible leon of Nemea, of which, since that day, he wore the fleece.
In the second one he might kill the Hydra, a bloodthirsty monster, and in this duty he was obstaculated by a crab. At the end, also thanks to the help of his coachman Iolaus, he succeeded in his task. Both the Hydra and the Crab are represented in the sky.
The fiftht labour consisted in cleaning King Augias stables. He got this by deviating the water-courses of two rivers.
In the tenth one Hercules might steal the cattle of Geryon, a monster with three bodies, that was killed by the hero with just one arrow.
Of the other two added labours, we remember the twelvth, the capture of the mythological guardian of the Hereafter, Cerberus, the three-headed dog. Hercules captured it with the force of his arms.

At the end, Hercules got back his freedom.

He married Deianira, daughter of King Aeneus. One day, as they might cross a torrent, they asked for help to the Centaur Nessus, to whom Deianira was entrusted; Hercules waded the torrent by swimming. But the Centaur tried to use violence to the woman, and so the hero hit him with an arrow wet in the Hydra's lethal blood. Nessus, deceasing, convinced Deianira of keeping some blood of his, telling her that it could make her husband faithful. The woman was convinced and one day, suspecting the unfaithfulness of her husband, strewed one dress of Hercules with the blood, and when he wore it, he felt terrible aches. Then he built to himself a funeral pile on Mount Eta, destroying his mortal body. Then his soul joined to the other gods and Zeus put his constellation in the sky.