What weapon does Thor use to kill Jormungandr?

Thor uses Mjölnir to kill Jörmungandr at Ragnarök.

Mjölnir is Thor’s enchanted hammer and his defining weapon in Norse mythology. The hammer can return to Thor after being thrown and is associated with thunder, protection, and the defense of the gods and humans. Thor is also said to use iron gloves and a strength-enhancing belt when wielding it.

At Ragnarök, Jörmungandr—the Midgard Serpent and one of Loki’s monstrous children—emerges from the sea and confronts Thor on the battlefield. Thor strikes the serpent with Mjölnir and kills it, but the victory is immediately fatal in turn: after walking nine steps, Thor collapses from the creature’s venom.

Readers sometimes confuse this weapon with Gungnir, Odin’s spear, or Gram, the sword associated with the hero Sigurd. Laevateinn belongs to a different mythic tradition and is not Thor’s weapon. The story’s key pattern is mutual destruction: the hammer defeats the serpent, while its poison kills the thunder god.