Mjölnir
Mjölnir, 'the grinder', is the war-hammer of the thunder god Thor, forged by the dwarven brothers Brokkr and Sindri as the prize of a wager Loki placed on his own head. Because Loki, in the shape of a fly, bit the smith's hand while he worked the bellows, the hammer's handle came out too short — which is why Thor wields it with one hand. The Prose Edda counts it among the god's three great treasures, beside the belt Megingjörð and the iron gloves Járngreipr; its head is sometimes said to be iron and the shaft wooden, and the hammer returns to the thrower's hand like a boomerang after striking.