Fafnir is a prominent figure in Norse mythology, known as a dragon who was once a dwarf. He transformed into a fearsome beast due to his insatiable greed for gold, particularly after acquiring a cursed treasure. This transformation symbolizes the destructive nature of greed and the consequences it brings. In the legend, Fafnir is ultimately slain by the hero Sigurd, who seeks to claim the treasure for himself. The tale of Fafnir serves as a cautionary story about the perils of avarice and the heroic journey, making it a significant part of the Völsunga saga.