Hydra

The Hydra is a vicious nine-headed monster that can grow back its heads.
== History ==
The Lernaean Hydra was born to Typhon and Echidna. While not the most powerful of its siblings, the Hydra was a fearsome and vicious monsters with nine heads (at birth). The monster terrorized the Kingdom of Lerna, chasing all of the inhabitants away with the toxic acid and fumes that it spewed at them and killing livestock. When one of the Hydra's heads was decapitated, two more snake-heads would grow in its place.
== Appearance ==
The Hydra is described in The Sea of Monsters to be a huge and scaly lizard-like monster with nine heads, each one diamond-shaped with a mouth lined with razor-sharp teeth. Each mouth spits toxic acid.
If one of its heads is severed, it immediately stops bleeding and swells like a balloon. The hydra grows two heads in the place of the lost one by splitting the severed neck in two and turning them into new heads.
In The Sea of Monsters, the Hydra is seen wearing a plastic bib reading "I'M A MONSTER DONUT KID!"
== Spoil of War ==
In the attic of the Big House in Camp Half-Blood, a Hydra head was left as a spoil of war. This Hydra was defeated in Woodstock, New York in 1969.
== Powers and Abilities ==
* It can spew acid from its mouth.
* It has multiple heads.
* Two heads will grow back for each head that is cut off.
* The monster as a whole possesses incredible superhuman strength.
== Trivia ==
* Hydra, the largest of the modern star constellations, is named after the monster.
* Hydra is also the name of a satellite of the dwarf planet Pluto.
* Hydra, a species of simple fresh-water animal, is named after the monster.
* In Greek Mythology, the Hydra terrorized the Kingdom of Lerna, so it is fully called the Lernean Hydra.
* The Hydra is the only monster which reforms in The Heroes of Olympus series after being defeated in the Percy Jackson and the Olympians series.
* The Hydra did not have one immortal head in Percy Jackson and the Olympians: The Lightning Thief.
* The existence of the red-bellied hydra confirms that there are multiple hydras in the riordanverse, unlike actual Greek mythology in which the Lernean Hydra is the only hydra