Mjolnir, which first appears in Journey into Mystery #83 (Aug. 1962), was created by writers Stan Lee and Larry Lieber and designed by artists Jack Kirby and Joe Sinnott.

Mjolnir is typically depicted as a large, square-headed gray sledgehammer, with a short, round handle wrapped in brown leather, culminating in a looped lanyard.

Mjolnir debuted in Marvel Comics title Journey into Mystery #83 (Aug. 1962), being the means by which physician Donald Blake transformed into thunder god Thor Odinson (by striking it on the ground).

Loki panics at the sight of the treasures, and, afraid he will lose the wager, transforms himself into a gadfly and stings Eitri's assistant on the brow as he is working the bellows for the forge.

The ruler of the Norse gods, Odin, uses the hammer – called Mjolnir ("Grinder") by Eitri – and eventually passes it to his son Thor, on the condition that he first prove he is worthy to wield the weapon.

[7] In the second volume of Thor, another version of the hammer's origin is depicted when Odin orders the dwarven blacksmiths Eitri, Brok and Buri to forge Mjolnir using the core of a star.

[17] After this the Donald Blake persona disappeared (eventually returning from the after life[18]), and Thor assumed a civilian identity simply by changing into modern clothing (carrying Mjolnir concealed within a duffel bag).

[19] The enchantment eventually changes: during the Original Sin storyline, Nick Fury whispers an undisclosed secret to Thor that causes him to lose the ability to pick up Mjolnir.

[21] The hammer is subsequently picked up by an unknown female – later revealed to be Jane Foster – who inherits the power and title of Thor, with the inscription changing to read if she be worthy.

[46] During the War of the Realms storyline, Thor is able to channel the power of the ancient Mother Storm to reforge Mjolnir, declaring that Gorr was right and vowing to prove himself better than the gods who had come before.

Other Marvel characters have lifted Mjolnir not through worthiness but through technicalities such as absorbing Thor's powers, including the Air-Walker, Awesome Android, Magneto, Rogue, Wonder Man, and Doctor Doom.