Odin and his brothers killed someone to create the universe.
In the beginning, the first cow, Audhumla, licked a salt block that became Búri, one of the foundation gods of Norse mythology. Búri had a son named Bor. Bor had three sons: Odin, Vili and Vé. So, untangling the family tree, Odin is the cow's great-grandson. Or, Odin is Búri's grandson.
In any event, the three brothers got together and killed Ymir, the first being. They used his body to create the universe.