Hreiðmarr was the father of Fafnir, Ótr, Lyngheiðr, Lofnheiðr and Regin. He owned a house of glittering gold and flashing gems built by Regin and guarded by Fafnir. After Otr was accidentally killed by Loki, the Æsir repaid Hreiðmarr with Andvari's gold and the cursed ring Andvaranaut, a magical ring that can make gold. Fafnir and Regin later killed Hreiðmarr for the magical ring. Fafnir decided he wanted Andvaranaut for himself, so he turned into a dragon and drove Regin away. Fafnir guards the treasure until Sigurd arrives and delivers a fatal blow to the dragon.