Who is Heracles from Theogony and Works and Days and what is their importance?

Heracles is the son of Zeus and Alcmena; he is said to be Zeus' favorite son. He is born in the fourth generation and is a demi-god. He kills the three-headed Geryones, the child of Chrysaor and Callirhoe. He vanquishes Orthus, Eurytion, Hydrea, the Neamean lion and many other monsters that plague mankind. Heracles also frees Prometheus from his daily torture of having his liver eaten. After his toils, Heracles becomes immortal and marries his half-sister Hebe, becoming Hera's son-in-law.