Hercules and Hydra
Heracles (Roman Hercules), a divine hero in Greek mythology, is the son of Zeus and Alcmene.
Besides an Olympian champion, he was the God of heroes, sports and divine protector of mankind.
Driven mad by Hera, who never stopped hating him, Heracles killed his own six sons. After recovering his sanity, he deeply regretted his actions and traveled to Delphi to inquire how to carry out his penance. The oracle advised him to live at Tyrins and serve King Eurystheus for 12 years, performing any labour he was ordered to.
Heracles loathed serving a man he considered far inferior to himself. Yet, afraid to oppose his father Zeus, he eventually placed himself at Eurystheus disposal, for whom he had to accomplish 12 labours.
The second one of these seemingly impossible duties was to conquer the nine headed Lernean Hydra. In Greek mythology, Hydra was an ancient nameless serpent-like water beast. It possessed reptilian traits with many heads (for each head cut off, two more would grow) and a poisonous breath, so virulent that even her tracks were deadly.
Its lair was the lake of Lerna. Beneath the waters was an entrance to the Underworld and the Hydra was its guardian.