Khthonius was one of the men born of the teeth of the teeth of the Ismenian Drakon. Kadmos having killed the Drakon planted and sewed the teeth. Khythonius was among those born from the teeth. When Kythonius and the other Spartoi emerged, Kadmos paniced and threw a rock at them. Khthonius and all the others believed one of their own had thrown it. A fight ensued and in the end five survived. The survivors were Ekhion, Pelorus, Udaeus, Hyperenor and Khthonius.