The myths of the Norse, also called the Vikings, are replete with heroes—among them Baldur, god of light and purity, Thor, who slew giants and other enemies of the gods with his invincible hammer; and the courageous Sigurd, nicknamed the Dragon-Slayer. Opposing the heroes were several villains, including Loki, who repeatedly betrayed his fellow gods, and Hel, who ruled an underground domain of dead souls.