Fafnir

Fafnir, a dragon in Norse mythology, was once a dwarf prince. He had two brothers, Regin and Otter. Otter was accidentally murdered by the god Loki, and the gods paid the family a massive tribute in cursed gold to make up for their unintentional crime. Fafnir decided he did not want to share, and stole the entire hoard. He was unaware of the curse, however. Soon after he hid his ill-gotten spoils, he transformed into a hideous dragon. Fafnir as a dragon was a hideous, sluggish serpent that breathed out large amounts of flame and toxic smoke. He was about 40 feet long and had wings, though he was not seen to fly. He was eventually killed by Siegfried, Regin's human foster son, who hid in a pit under a trail the dragon frequently used and stabbed it in the heart with a sword as it passed overhead. Siegfried cooked and ate the dragon's heart, which allowed him to speak with birds. He thus learned from some crows that the treacherous Regin planned to kill him and obtain Fafnir's hoard for himself. Siegfried killed Regin and claimed the treasure, though some versions of the tale say that Siegfried as well fell victim to the curse.