The Hydra of the lake Lerna is the most known dragon in Greek mythology. According to the myth, Hydra had the body of a huge snake and nine heads. For every head chopped off, Hydra could regrow two other heads. So it was impossible to be defeated. That beast was killed by Hercules with the help of his nephew Iolaus. So first Hercules cut off one head, using the sword that Athena had given to him. Then Iolaus burn the neck with fire, and that way the new heads couldn’t be regrown. Hercules cut off all the heads of Hydra. He placed the last, central head which was immortal under a big rock and dipped his arrows in Hydra’s poisonous blood. The goddess Hera who hated Hercules, placed Hydra in the sky as a constellation.