One source has it that she was the daughter of the primordial deity Nyx (night), that emerged from the blood of the Titan Uranus after he was castrated by his son Cronus. Another source names Gaea and Aether as her parents. Hera asked Lyssa to take command of the hero Heracles and overpower him with madness. Lyssa initially said that she was not fond of visiting the homes of men, nor use her powers to turn friends against each other. She unsuccessfully tried to give the task to Iris, so she had no choice but to fulfill the command of Hera. She sent Heracles into a fit of madness, during which he killed his wife Megara and his children.
Another myth in which Lyssa participated was that of the hunter Actaeon. While hunting in the woods with his dogs, he came across the goddess Artemis, who was bathing naked in a lake. Artemis spotted him and, enraged, she turned him into a stag. Lyssa then inflicted rabies on his dogs and tore him apart.