Fáfnir

In Germanic heroic legend and folklore, Fáfnir is a worm or dragon slain by a member of the Völsung family, typically Sigurð. In Nordic mythology, he is the son of Hreiðmarr, and brother of Regin and Ótr and is attested throughout the Völsung Cycle, where, Fáfnir slays his father out of greed, taking the ring and hoard of the dwarf Andvari and becoming a worm or dragon.