Dark Kingdom: The Dragon King (also known, in different cuts, formats and markets, as Ring of the Nibelungs, Die Nibelungen, Curse of the Ring and Sword of Xanten) is a 2004 German television film directed by Uli Edel and starring Benno Fürmann, Alicia Witt, Kristanna Loken and Max von Sydow. The film is based on the Norse mythology story Völsungasaga and the German epic poem Nibelungenlied, which tells the mythological story of Siegfried the Dragon-Slayer. Richard Wagner's music dramas Siegfried and Götterdämmerung are based on the same material. Dark Kingdom: The Dragon King was written by the husband and wife team of Diane Duane and Peter Morwood and is a Tandem Communications production. It was filmed entirely in South Africa.

Dark Kingdom: The Dragon King had a theatrical release in the United Kingdom on November 19, 2004. The German-language version, Die Nibelungen, was shown on the German television channel Sat.1 on November 29 and 30, 2004. It was the highest-rated mini-series on German television that year. On December 23, 2005, Channel 4 showed the entire series in one evening under the title Sword of Xanten, describing it as a "megafeature". It was shown on the SciFi Channel on March 27, 2006, retitled Dark Kingdom: The Dragon King for the United States audience, and minus about one hour of material.