Valkyries are women warriors from the sky and guardians of Odin. They wear helmets with small white bird wings, armor, long white skirts, sandals, and wield a sword and shield. They ride on flying horses and are based on the same Valkyries from Norse mythology.
Expanded Animated Universe
Appearing in Season 10 of the Expanded AU, they also train little Valkyries how to be warriors and - when the time comes - to be new guardians. One of them is Artemis: a young Valkyrie who first appears in the episode, "The Littlest Valkyrie."