In Norse mythology’s Ragnarok, Thor kills the world serpent Jörmungandr but dies from its venom.
Jörmungandr, also called the Midgard Serpent, is one of Loki’s monstrous children. Odin casts it into the sea surrounding Midgard, where it grows large enough to encircle the world and grasp its own tail. Thor and the serpent are longstanding enemies in Norse myth.
During Ragnarok, Thor finally defeats Jörmungandr with his hammer Mjölnir. The victory is brief: the serpent’s poison reaches him, and the god takes only nine steps before collapsing and dying.
This episode is separate from Thor’s earlier fishing expedition, when he tried to lift the serpent using an ox head as bait. That story is often depicted in Viking Age art and helps establish the cosmic scale of their final battle.