Cephalus was Zeus' personal huntsman. He was sent by Zeus to bring Hercules from Earth back to Olympus. He was recalled by Zeus after seeing the nobility of the Sub-Mariner who had risked his life for Hercules in battling the Huntsman.
Cephalus was empowered by Zeus and endowed with a fraction of his divine might when freeing him from the Underworld. Zeus gave him immortal skill to track his victims and the power to create terror in the one he stalked. Much of Cephalus' strength came from his spear/staff, the physical embodiment of his lords power which he could recall back whenever he hurled it.