The Hydra is a giant snake-like beast issued from Greek mythology. It is never seen in the series, but is mentioned in "Being Human" from Season 2. Because they are never seen, their true form remains unknown.
Although it is never seen, it is safe to assume that the Hydra has a long serpent-like body and is often described as either a bipedal or a quadruped. It starts with only one head (or more depending the version of the myth), but can easily grow some more.
The main power of the Hydra is its ability to grow two more heads when a single one is cut. This power is infinite, so as long as its heads are being cut, more will grow back almost instantly. Its breath is extremely deadly and poisonous. Unfortunately, the immortal head (which was the central head and was larger than the others) can never be completely destroyed.
In the series, Hydra scales, as well as other rare ingredients, are used in an ancient ritual to revive the dead.
Life in the Magical World
Aside from "Being Human", the Hydra is never mentioned or heard from again in the entire series. Since the Hydra is a very dangerous creature, it is possible that it is kept in captivity to keep it from running on a rampage. It is also possible that it remains hidden in its homeland, near the former Lake Lerna now evaporated.
The Hydra is not an extinct species since its scales are often used as ingredients for rituals, potions and other magical concoctions.
- In Greek mythology, a Hydra was the second of the 12 labors Hercules had to overcome;
- Hercules killed a Hydra by cutting its heads and then Iolaus was told to burn its neck stumps, thus rendering it impossible for the beast to grow new heads (in other words, the burning stumps will prevet the heads from growing back). Also, Hercules was wearing his protective lion-skin (Nemean Lion) and holding his breath during his fight with the Hydra.
- In the series, Bananas B and Councilor Chang steal a bottle of Hydra scales.
- The Hydra's immortal head cannot be removed by any weapon that a warrior makes. In some tales, its head was made of gold. To defeat the immortal head, Hercules tore it off with his bare hands and buried it deep underground where it will never harm anyone again.
- In some tales, the Hydra looked like a huge water serpent, but in others it had the body of a dog.
- The Hydra was known to be a sibling of Cerberus.