Mjollnir

Mjollnir was Thor's magic golden hammer. The hammer came about when Loki cut off the hair of Thors goddess wife Sif. To save his life from the angry thunder god, Loki traveled to the land of the dwarfs where the Sons of Ivaldi made new hair for Sif out of stands of magical gold . They also made a magical golden long boat for Frey and the magical golden war spear Gungnir for Odin the Allfather. On the way back to Asgard, Loki visited the dwarfs Brokk and Eitri and entered a dangerous bet. Loki bet that his gifts for the gods from the Sons of Ivaldi where better than any gifts that Brokk and Eitri could make, and offered his head should he loose.

Brokk and Eitri took the bet and started work right away. Loki grew worried and turned himself into a horsefly to watch the two work. As they made their first item, Loki bit Brokk on the hand so that he could not fan the mighty fire heating the forge, but Brokk didn't notice and a fine magical golden boar named Gullinbur for the god Frey.

Brokk and Eitri started work on the second item as Loki bit Brokk on the neck to stop him from fanning the fire, but Brokk didn't notice and finally they finished a magical golden arm ring named Draupnir for Odin.

Brokk and Eitri started work on the final item, and when they where about finished Loki bit Brokk on the eyelid. Brokk stopped fanning the fire to wipe the blood out of his eye just long enough for the fire to cool down too much to finish the third item, a magical golden hammer called Mjollnir for Thor. It was a good hammer, but the handle was just a little too short.

Mjollnir won the bet for Brokk and Eitri because it would hit any object Thor would throw at and return to his hand, But Brokk could not collect Loki's head because it would mean cutting Loki's neck, and his neck was not part of the deal. So Brokk sewed Loki's mouth shut to teach him a lesson on when to use it, and most importantly, when not to.

Thor used his hammer many times in battle against the giants. One time it was stolen by Thrym, the king of the frost giants, and buried nine miles under the earth. The only way he would return it to the Thunder god was if he could marry Freya. Thor disguised himself as Freya and Loki as her maidservant and traveled to Jotunheim to retrieve the hammer, which they did at the cost of Thrym's life.

Mjollnir also carved out three valleys in a mountain near Utgard when Thor threw his hammer at a giant named Skrymir, who was really Utgard-Loki in disguise and using the mountain as a shield.

Thor will carry the mighty hammer into the final battle called Ragnarok where he will use it to crush the world serpent Jormungand's head, but he will be poisoned by the mighty serpent and die after taking nine steps.

This will not be the end of Mjollnir though. The hammer will be passed along to Thors two sons named Modi and Magni to defend the worlds yet to come after Ragnarok.