In Norse mythology’s Ragnarok, which world-serpent fights Thor?

In Norse mythology’s Ragnarok, Jörmungandr is the world-serpent that fights Thor. The serpent rises from the sea, and Thor kills it with his hammer before dying from its venom.

Jörmungandr is also called the Midgard Serpent because it encircles the human world. Odin’s fear of the serpent’s eventual power leads him to cast it into the ocean, where it grows until it surrounds Midgard and grips its own tail.

The serpent and Thor have several earlier encounters. In one famous story, Thor tries to lift it while it is disguised as a cat; in another, he nearly catches it while fishing with the giant Hymir. These episodes foreshadow their final Ragnarok battle.

Jörmungandr is distinct from Fenrir, the giant wolf who kills Odin, and from Níðhöggr, the serpent-dragon associated with Yggdrasil. Their similar monstrous forms can cause mix-ups, but only Jörmungandr is Thor’s Ragnarok opponent.