The Poetic and Prose Eddas are ancient Norse texts containing information about the origins of the universe according to Norse mythology. Actually, you can check out the myth right here at Shmoop, but we'll give you a quick summary anyway: Odin and his brothers, Vili and Ve slay the giant Ymir and use his blood and bones to fashion the world and its inhabitants. The end.
The take away message here is that killing people and using their bodies to make the world is something of a theme among creation myths. In the case of the Olympians, the world actually already existed, but the killing – or at least the fighting – seems to remain an important part of describing the creation of the universe. It's interesting to note that much of the rest of Norse mythology is filled with stories of war between the Aesir, the Gods, and the Jotun, the Giants. The feud between Aesir and Jotun bears a striking resemblance to the war between the Titans and the Olympians. Pretty nifty stuff, if you ask us.