Ymir and the Jotuns

In Norse Mythology, the first being to come into existence war Ymir, a massive frost giant so large that his skull was used to make the sky when Earth was created. He was born directly out of Ginungagap, a gaping pit of chaos, and he was the first of the race that would be the archenemies of the Norse gods. Ymir was massively strong, and posessed the unusual ability to generate other, smaller Jotuns (Norse frost giants) while he was sleeping. Several other ancient Jotuns were born from Ymir's perspiration as he rested. Eventually, after the first gods were born, three of their most powerful, Odin, Hoenir and Lodur, challenged Ymir's tyrannical rule over the young universe and killed him. They used his body to make Earth. However, the other Jotuns lived on, and from then on they hated the gods even more. They made their home in the icy mountains and were always preying on gods and mortals alike. This will continue until Ragnarok, the Norse apocalypse, at which point they will storm Asgard, cidatel of the gods. In the massive battle that will follow all of the Jotuns and all but a few of the gods will be killed.