Mjolnir

Mjölnir is an item featured in the folklore of Norse mythology and is often depicted as a war hammer owned by Thor - the Viking Norse God of Thunder. Some stories relating to Mjolnir, refer to it as either a club or a battle axe. Fictionalized accounts of Mjolnir have appeared in many different media, but the most popularly known of which is the version used by the Marvel Comics superhero Thor Odinson.

The Marvel Comics version of Mjolnir first appeared in Journey Into Mystery, Volume 1 #83 in August, 1962. Almost every different interpretation of the Thor character shows him using a version of Mjolnir, usually with a distinctive appearance to distinguish it from Marvel's Mjolnir.

Description
Mjölnir is a Viking war hammer with a heavy rectangular head and a handle that measure roughly one meter in length. A leather thong is attached to the bottom of the handle, which enables Thor to swing it about in a circle to gather momentum. Thor uses the hammer to channel his powers as the Norse God of Thunder and swinging the hammer allows him to summon thunder, lightning and the storm.

The Hammer of Thor was a gift from his father, Odin - All-Father of the Asgardian Gods. Odin instructed three dwarf blacksmiths named Buri, Brok and Eitri to craft the finest weapon they could - one befitting a Prince of the Realm. The head of the hammer was forged from a mystical metal called Uru and is virtually unbreakable. Before presenting the hammer to Thor, Odin placed an enchantment upon it, which is inscribed upon the face of the hammer:

"Whosoever holds this hammer, if he be worthy, shall possess the power of ... Thor"

The enchantment only appears visible when held in the hands of those seeking to harness the power of Thor. During combat scenarios or when it is at rest, the inscription cannot be seen.

In addition to calling forth the storm, the hammer has also been used to transform Thor into the mortal Donald Blake. When Thor was disguised as Blake, the hammer too would assume it's own disguise, that of an ordinary walking stick. In the years of Thor's superhero career on Earth, the hammer possessed a restriction that if Thor should be separated from the hammer for more than sixty seconds, he would turn back into Donald Blake and Mjolnir would resume the form of a walking stick.

By spinning the hammer in a circular motion by it's thong and then thrusting it skyward, Thor is able to fly vast distances and at great speed. When he throws the hammer, it will always return to his hand upon summoning it, except in the case where an obstacle greater than Thor's strength or Odin's enchantment might impede it.

Marvel Cinematic Universe
Mjolnir made its first big-screen appearance in the 2011 feature film adaptation of Thor, which is the fifth film in the Marvel Cinematic Universe series of films. In the film's mythology, Mjolnir was forged in the heart of a dying star.

Odin, king of Asgard bequeathed the hammer to his son, Thor Odinson, with the presupposition that Thor would one day ascend to the throne of Asgard. A youthful Thor however was often brash and impetuous. On the eve of his coronation, Thor went against the orders of his father, to investigate the attempted theft of the Casket of Ancient Winters by the Frost Giants of Jotunheim. He wielded Mjolnir in battle, hurling it through the mouth of a great beast. Because of his arrogance, the tenuous truce between the Asgardians and Frost Giants was now broken. As punishment, Odin stripped him of his power and sent Mjolnir to one of the Nine Worlds - Midgard, or as others may know it, Earth. Odin placed an enchantment on the hammer, decreeing that only one who was deemed worthy could even pick up the hammer, much less use it.

The hammer was discovered on earth centuries later buried deep in a crater in New Mexico. It was found by agents of the national spy agency S.H.I.E.L.D. in the year 2010. S.H.I.E.L.D established a bunker surrounding the site, and labored to unearth the hammer, but because of Odin's decree, nobody could move it.

Thor eventually appeared on Earth, but without the benefit of his Godlike power. Through a series of noble acts, Thor regained his worthiness and was able to remove Mjolnir from the crater. He used it to destroy an Asgardian construct known as the Destroyer. Thor returned to Midgard a year later, and briefly engaged in a scuffle with the Earth heroes Captain America and Iron Man. When Cap commanded him to put the hammer down, Thor obliged him, pounding it upon Captain America's shield. Fortunately for Cap, his shield was unbreakable, but the impact created a massive shock wave in the forest.

Thor later used Mjolnir to knock down a rampaging colleague known as the Hulk. It was likely the hardest the Hulk had ever been hit up until that point.

Thor also used Mjölnir against the Marauders during the War of the Realms, notably destroying a Kronan with one hit, as well as the Dark Elves when they invaded Asgard. Mjölnir was also used to throw lightning at Malekith, burning the right side of his face.

When dealing with the Aether, Mjölnir's lightning managed to shatter it into shards, only for it to reform later Mjölnir was also no match against the Kursed Algrim who simply deflected it when Thor summoned it to strike him. Mjölnir, however worked greatly against Malekith on Earth, with Thor being able to deflect many of his Aether powers. The constant shifting of the fighting between worlds caused Thor and the hammer to become separated, but at the battle's apex, as Malekith unleashed the Aether to complete his plan, Thor was able to summon Mjölnir back to his hand and use it to bury the last of Erik Selvig's gravitational devices into Malekith's chest, allowing Jane Foster to transport the Dark Elf warlord to his death on Svartalfheim.

At a party held at Avengers Tower, members of the Avengers scoffed at the notion that no one could wield the hammer but for Thor. They all took turns trying to move it, and even Tony Stark with the benefit of his strength-enhancing gauntlet could not move it.