Dahak

Dahak, the One Evil God (previously called the One God or The One) was the impulse of destruction, a powerful, ancient evil being and a recurring character on both Xena: Warrior Princess and Hercules: The Legendary Journeys. Although his true form has only been seen once or twice on-screen, he possessed Iolaus' dead body. He impregnated Gabrielle with Hope, his one daughter and representative on Earth. He was one of the main causes of the Rift and the events that later led to Gabrielle's apparent death.