Heracles beautiful companion who was abducted by a nymph during the Argonauts' journey towards Asia. The Argonauts had docked at the island Chios and Heracles went to cut some wood in order to replace his broken oar. Hylas went to get some water, when the nymph Kypris saw him, fell in love, and embraced him - dragging him down into the well. Heracles was left behind since he would not stop looking for him.