This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Cacus (Roman)
In Greek and Roman mythology, Cacus was a fire-breathing giant and the son of Vulcan (Plutarch called him son of Hephaestus). He was killed by Hercules after terrorizing the Aventine Hill before the founding of Rome. Cacus lived in a cave in Italy on the future site of Rome. To the horror of nearby inhabitants, Cacus lived on human flesh and would nail the heads of victims to the doors of his cave. He was eventually overcome by Hercules.
Aeneas by Evander, describes Cacus as a “foul-featured, half-human monster” who lived in “a cave which the rays of the Sun never reached.” The cave of Cacus is believed to be situated on the Aventine Hill. Cacus was not only a monster in form, but also in behavior. Evander states that the floor of Cacus’ cave was “always warm with freshly shed blood,” whilst “the heads of men were nailed to his proud doors and hung there pale and rotting.”