Valkyrie appears as an NPC in the video game Marvel: Ultimate Alliance.
Brunnhilde was selected by Odin, King of the Gods of the realm of Asgard, to lead the Valkyrior (the Choosers of the Slain), a group of warrior goddesses who would appear over the battlefields of mortal worshippers of the Asgardian gods and choose which of the fallen were worthy to be taken to Valhalla, the land of the honored dead. Brunnhilde served capably in this capacity for centuries.
According to a sentient, disembodied eye that claimed to have once belonged to Odin, the Asgardian monarch once gave his son Thor the mortal identity of the warrior Siegmund. Circumstances forced Odin to decree that Siegmund must be slain. Brunnhilde, recognizing that Odin was acting against his true wishes, sought to protect Siegmund, but Odin himself then caused Siegmund's death. Brunnhilde helped Siegmund's pregnant lover, Sieglinde get to safety. As punishment for her defiance, Odin removed Brunnhilde's Asgardian powers and immortality and cast her into a trance. She was eventually awakened by Siegfried, the son of Siegmund and Sieglinde and another mortal incarnation of Thor.
Brunnhilde and Siegfried became lovers, and she made him invulnerable so long as his back was not turned on his foe. Siegfried fell under the influence of magic and betrayed her. He was later murdered, and Brunnhilde, still in love with him, leaped into his blazing funeral pyre (this part of her background was based on the Volsunga saga). Odin restored both of them to live, restoring their Asgardian roles and powers, but removing their memories of their earthly lives. It is unclear how much truth if any, there is to this account by the eye. Brunnhilde and her fellow Valkyries continued to gather heroic mortal warriors for Valhalla until roughly a millennium ago when Odin was forced to cease virtually all interaction with the Earth in accordance with a pact that he and the leaders of Earth's other pantheons of gods made with the extraterrestrial Celestials. From then onward, the Valkyries could only choose slain heroes from among fallen Asgardian warriors.
Brunnhilde was bitter over being barred from choosing warriors on Earth and roamed Asgard in pursuit of something meaningful to do. In a tavern on the outskirts of Marmoragard, Brunnhilde encountered Amora the Enchantress, who offered her a life of adventure. For several weeks, Brunnhilde accompanied the Enchantress on her conquests. Brunnhilde soon discovered Amora's immoral nature and tried to end their partnership. In response, the Enchantress trapped Brunnhilde within a mystic crystal of souls. While Brunnhilde's body remained in suspended animation, her immortal soul became Amora's plaything. Over the centuries, the Enchantress used Brunnhilde's spiritual essence to give the Valkyrie's powers to herself or to her pawns.