The Valkyrior or "Choosers of the Slain" are members of an extra-dimensional race of beings known as the Asgardians, who were worshipped as gods by the Scandinavian and Germanic people of Western Europe. The Valkyries were not worshipped as gods with the rest of the Asgardians, but were rather assigned the role of guiding the honored dead Valhalla, the sacred hall of Odin for those noble warriors who had gained the favor of the Asgardian gods. Those who did not gained the favor of the gods were instead relinquished to the realm of Niffleheim ruled by the goddess, Hela, while sinners and criminals were relegated to Hel.

The Valkyrior possess certain superhuman physical attributes akin to the other known gods of Earth. They are extremely long-lived, but they are not immortal like the Gods of Olympus; they age at an extremely slow rate upon reaching adulthood, and they cannot die by any conventional means. They are immune to all Earthly diseases and are resistant to conventional injury. If one of the Valkyries were somehow wounded, their godly life force would enable them to recover with superhuman speed. It would take an injury of such magnitude that it dispersed a major portion of their bodily molecules to cause them a physical death. Even then, it might be possible for a god of significant power, such as Odin or for a number of Asgardian gods of equal power working together to revive them. They also possess superhuman strength; the typical Asgardian goddess can lift (press) about 30 tons, but the Valkyrie are significantly stronger, capable of lifting up to almost 40 tons. Their Asgardian metabolism provides them with far greater than human endurance in all physical activities. (Asgardian flesh and bone is about three times as dense as similar human tissue, contributing to the superhuman strength and weight of the Asgardian gods.)

The Valkyries have inherent mystical powers allowing them to perceive supernatural phenomenon, especially to perceive astral spirits (ghosts) of the dead and sense when mortal beings are near death; a perception that appears as a glow around the form of a person about to die. Beyond Asgard and on Earth, they often appear only as shades (astral forms), although Brynhilda has appeared several times on Earth in a physical form. They are extra-ordinary warriors wielding swords and shields and usually transport themselves aloft on winged horses which attain an astral form with them beyond Asgard. According to myth, the Valkyries have also sometimes appeared riding wolves or in the form of ravens. Among the mortals the Valkyries have delivered to Valhalla are the Asgardian hero, Grim Magnus, and the Visigoth warrior, Harokin.

The Valkyries are the daughters of Odin, Chieftain of the Asgardian Gods, and the earth-goddess, Nertha, sister of Njord, the god of sea and storm. Odin instructed them to collect the honored dead, but they often went against Odin's whims to select favorites. Brynhilda reportedly became lovers with the Fourth Century hero Siegfried, but it seems she no longer has any of these memories. Known as the Valkyrie, she has appeared on Earth several times as a member of the Defenders and as an ally of Thor against various threats to Earth and the Asgardian gods. During World War Two, Adolf Hitler reportedly used the Spear of Destiny to call upon Thor to aide the Third Reich. Appearing amidst the Valkyries to rally to Germany's defense, Thor however refused after realizing they were mortal men with evil motives. One of the Valkyries named Gudrun, however, stayed behind as a member of Axis America, a group of Nazi-superhumans who clashed with the All-Star Squadron.

In recent years, the Valkyries have had several confrontations with Hela, the goddess of the dead, who seeks to conquer Valhalla and add it to her realms of the dead. During one of Hela's attacks on Valhalla, Brynhilda refused to rally with the other Valkyries in order to join the Defenders against the Six-Fingered Hand. She was briefly replaced as leader of the Valkyrior with Valtrauta, but Brynhilda regained leadership again to join forces with them and force Hela back to her realm.

In ancient times, German writers claimed there were two kinds of Valkyrior: nine who were of divine birth and the rest were half-mortal, usually called "vaetter-maidens." Three such mortal Valkyrior named Olrun, Alvitr and Svanhit appear in myth as lovers of the blacksmith Weyland and his brothers, Egil and Slagfinn. Another mortal Valkyrie was Danielle Moonstar of the New Mutants when the young heroes were lost in Asgard. Moonstar became friends with Mista of the Valkyrior and discovered the winged horse, Brightwind, who accepted her as its master, but she surrendered him to the Valkyries when she departed Asgard. Moonstar soon called upon the Valkyrior to defy Loki attempting to remake Storm of the X-Men into an erstwhile ally. Brightwind soon brought Moonstar back to Asgard when Hela took possession of the Valkyrior with a spell that also subjugated Moonstar and led them to seize Asgard while Odin was in his Odin-sleep. The New Mutants followed Moonstar into Asgard and led the Asgardians against Hela and broke her hold over the Valkyrior.

During the time the Asgardians were lost on Earth as mortals, the Valkyrior were taken hostage by Malekith of the Dark Elves working for Hela. He began by draining off their life-energies and unique Valkyrie-powers for Hela, but Brynhilda escaped and imparted part of her life-force to Danielle Moonstar. Danielle brought Cable and X-Force to Asgard to defeat Malekith and restore the Valkyrior to full power. Afterward, the Valkyrior aided the Defenders against Hades and his army invading Earth.

In recent years, the Valkyrior appeared in Ymir-Krul in Nidavellir to honor the memory of Eitri, the leader of the dwarves who had lent a part in the creation of Mjolnir. Loki meanwhile began his siege of Asgard, and while defending Asgard, Brynhilda passed chiefdom of the Valkyrior to Sif to guide them against Loki's forces laying siege against Asgard. After they were struck down attacking Surtur, Thor severed the threads of destiny keeping the Asgardians trapped in recurring cycles of Ragnarok. Brynhilda's essence meanwhile continued to co-exist within Samantha Parrington as the Valkyrie replacing Barbara Norris as her mortal incarnation with the Defenders. A year after, the Asgardians returned to life in Latveria. Restored to life as well, the Valkyrior have joined with Thor in the rebuilding of Asgard and against the Disir.

It should be noted there are a few other individuals who claimed to be Valkyries but were either imposters or charlatans. One of these individuals was Amora the Enchantress trying to rally the women in the Avengers against their male teammates. Another Valkyrie was a mortal performer in Calliope's Carnival and Circus. Amora's sister, Lorelei, also briefly became trapped in the form of Brynhilda. Another Valkyrie appeared as a figment of Thor's imagination as a physical representation of his mental instability, but she was destroyed by Odin.

First Appearance: Journey into Mystery I #92