In Greek mythology, Typhon (Typoeus) was the son of Gaea, the earth goddess, and Tartaros. The goddess birthed him in a last ditch effort to defeat the Olympians who were trying to destroy her sons, the Titans.
It is said that Typhon was a monstrous immortal giant with a hundred snaky heads that never rest. He was so large that his head was said to brush the stars and his eyes were flashing fire. Well, for a more precise description, let's just quote the text:
'the hands and arms of him are mighty, and have work in them, and the feet of the powerful god were tireless, and up from his shoulders there grew a hundred snake heads, those of a dreaded drakon, and the heads licked with dark tongues, and from the eyes on the inhuman heads fire glittered from under the eyelids: from all his heads fire flared from his eyes' glancing; and inside each one of these horrible heads there were voices that threw out every sort of horrible sound, for sometimes it was speech such as the gods could understand, but at other times, the sound of a bellowing bull, proud-eyed and furious beyond holding, or again like a lion shameless in cruelty, or again it was like the barking of dogs, a wonder to listen to, or again he would whistle so the tall mountains re-echoed to it'
Apollodoros, Bibliotheca, 1.6
Typhon also mated with Echidna and they were so fearful (or maybe just ugly) that, when the gods saw them together, they changed into animals and fled in terror.
Zeus, master of Olympus, regained courage and faced the monsters. The battle was terrible and almost every creature on earth was killed by the demon.
Typhon captured Zeus and removed the tendons from his hands and feet but, when everything seemed hopeless, Hermes succeeded in freeing Zeus from the creature. Typhon then tore up huge Mount Etna to hurl across the gods. Zeus, with anger, proved his supremacy by defeating Typhon and the evil creature was buried under the mountain. The legend says that the monster is still kept under mount Etna, in Sicily and his anger is the cause of the volcano's eruptions.
Echidna, who escaped destruction, gave birth to Typhon's monstrous childs: Cerberus, Sphinx, Chimera, Orthrus , Hydra, the Nemean Lion and the Eagle of Prometheus.