In Siegfried mythology, the hero known for slaying the dragon Fafnir is Siegfried (or Sigurd in Norse lore). He defeats Fafnir, who had transformed into a dragon to guard his ill-gotten gold. This act not only showcases Siegfried’s extraordinary bravery but also symbolizes the triumph over greed and corruption. The victory grants him immense wealth and power, further entwining him with themes of heroism and fate, as well as the complex relationship between power, treasure, and morality within the mythic narrative.