Hydra

The hydra (greek: Ὕδρα) is a huge lizard with one or several long snake-like heads. It has powerful regenerative powers and poisonous breath. While some start out with just one head, their greatest strength is their ability to grow two new, for each that is chopped off.

Source
The hydra is the offspring of Typhon and Echidna. The hydra's siblings are the Chimera, Cerberus, Sphinx and Orthrus. The earliest mention is in Hesiod's poem Theogony around 700 BC.

Media
Hydras appear in the following media:

Books

 * The Halfling's Gem: The Legend of Drizzt, Book 6, by R.A. Salvatore, hero Wulfgar fights a mighty hydra in this book from "The Forgotten Realms".

Movies

 * Hercules - 1997 - the movie adaptation by Walt Disney Pictures / Walt Disney Feature Animation

Games

 * Castle Age
 * Dungeons and Dragons Universe, the monster made several appearances in books, games, video-games;
 * Gems of War
 * Might and Magic VII
 * Dungeons and Dragons Universe, the monster made several appearances in books, games, video-games;
 * Gems of War
 * Might and Magic VII
 * Gems of War
 * Might and Magic VII
 * Might and Magic VII
 * Might and Magic VII
 * Might and Magic VII
 * Might and Magic VII
 * Might and Magic VII