Mótsognir is the creation of Odin and his brothers, Vili and Vé, who fashioned him out of Ymir's blood and bones in the form of a maggot. These Æsir later gave him a roughly humanoid appearance and a human-like intelligence, which the rest of the dwarfs ("dvergar") later inherited.
This interpretation of the origin of the dvergar is given in Snorri Sturluson's Prose Edda (Gylfaginning 14), and is quite disputed. The original text in the Poetic Edda poem Völuspá can easily be interpreted to tell a story of how the dvergar and the Æsir together gave shape and life to humans.
- The prefix Mót- means battle, the affix -sognir means roarer