Kili Surtr Muspelheim (キーリ・スルト・ムスペルヘイム, Kiri Suruto Musuperuheimu) is one of the main female characters in the Unlimited Fafnir series. She is the most dangerous among the Ds labeled as 'disasters' and the leader of the Sons of Muspell, a Dragon-worshiping cult. Although an antagonist at first, she joins forces with Yuu Mononobe and his friends on many occasions and eventually enrolls in Midgard upon being marked as one of Yuu's mates, becoming a member of Brynhildr Class.