Cacus was a fire-breathing giant from Roman mythology and an enemy of Hercules. He was the son of the Roman god Vulcan.
Cacus lived in a cave on the Palatine Hill in Italy, where Rome would later be founded. A cannibalistic monster, Cacus would drag his victims back to his cave to devour them, afterwards nailing the victim's heads to his door and leaving them there to rot. He killed enough people that the floor of his cave was constantly covered with fresh blood.
Cacus was finally destroyed when the hero Hercules passed through the area with the cattle he had stolen from Geryon, stopping to pasture them near Cacus' lair. While Hercules was sleeping, Cacus snuck out and stole away eight of the cows, pulling them by their tails so that their tracks would appear to lead towards the herd and would not be noticed. However, his scheme was foiled when, as Hercules was about to leave, the other cows began mooing in the direction of the cave and one of the ones Cacus had stolen lowed in reply.
Infuriated, Hercules stormed up to Cacus' cave with his club. Cacus ran and hid inside the cave, blocking the entrance with his boulder, but Hercules' supernatural strength enabled him to tear the roof off the cave and attack him that way. Cacus breathed fire towards Hercules, who responded by pelting him with tree branches and boulders. Eventually Hercules managed to leap into the smoke, aiming for where the smoke was heaviest so as to land directly on top of his enemy, and choked Cacus so hard that his eyes popped out of their sockets and all the blood in his throat was squeezed out. He then dragged his corpse out by the feet for nearby inhabitants to see.
