According to Wikipedia:
Brynhildr (sometimes spelled Brunhild, Brünnhilde, Brynhild) is a shieldmaiden and a valkyrie in Norse mythology, where she appears as a main character in the Völsunga saga and some Eddic poems treating the same events. Under the name Brünnhilde she appears in the Nibelungenlied and therefore also in Richard Wagner's opera cycleDer Ring des Nibelungen. She may be inspired by the Visigothic princess Brunhilda of Austrasia. The history of Brynhildr includes fratricide, a long battle between brothers, and dealings with the Huns.