Charybdis was an evil spirit of the seas and the daughter of Poseidon, the major Greek god of the Seas and Gaea, the goddess of the Earth.
Charybdis and Scylla were living together on either sides of the island of Sicily in Italy, spreading fear among the sailors crossing the island. Charybdis' particular task was to swallow water three times a day and then throw up, creating this way whirlpools in order to drown vessels that passed by.
Scylla and Charybdis are mostly mentioned in Homer's famous Epos, the "Odyssey".