In The Saga of the Volsungs, Sigurd’s dragon is named Fafnir. The saga presents Fafnir as the son of King Hreidmar, who becomes a dragon after greed and possession of the cursed Andvari treasure transform him.
Sigurd is guided by Regin, Fafnir’s brother, who forges the sword Gram. Sigurd digs a pit, hides in it, and kills Fafnir by striking the dragon’s heart from below. Afterward, Sigurd roasts and tastes Fafnir’s heart, gaining the ability to understand birds and learning of Regin’s betrayal.
This episode is one of the most influential dragon-slaying stories in northern European literature. Related versions appear in the Poetic Edda and in the Middle High German Nibelungenlied, although details and names vary between traditions.
Fafnir is often confused with Jörmungandr, the Midgard Serpent of the god Thor’s mythology. Jörmungandr is a gigantic world serpent, while Fafnir is the treasure-guarding dragon defeated by Sigurd.