Hydra

The Hydra is a serpent-like beast with nine heads. The Hydra's nine heads are used to symbolise the number nine in the runic alphabet.

Behind the scenes

 * In Harry Potter and the Half-Blood Prince, Severus Snape describes the Dark Arts as though they were a creature similar to the classical depiction of a hydra: one that regrows two heads for every one that is cut off.

Appearances

 * J. K. Rowling's Official Site