In Norse mythology’s Ragnarok, Surtr is the fire giant associated with the destruction of the Bifröst. He comes from Muspelheim and leads fiery forces into the final conflict against the gods.
Surtr is described as carrying a flaming sword and guarding the boundary of the fire realm. During Ragnarok, he advances with the fire giants and sets the world ablaze. The rainbow bridge Bifröst breaks as the forces of destruction cross or overwhelm it, though the sources do not present Surtr as an ordinary bridge-destroying character in every detail.
Surtr is often confused with Surt, a modern spelling variant of the same name. He is also distinct from Fenrir, the wolf who kills Odin, and Jörmungandr, the world-serpent who fights Thor.
After the battle, Surtr’s fire becomes part of the cosmic destruction that precedes renewal. His role connects Ragnarok with the fiery forces of Muspelheim rather than with the ocean or underworld.