From Old Norse. Literally means "Choosers of the slain." Disir who at Odin or Freyja's command, select the most heroic warriors on the battlefield to die and conduct their souls through the Underworld to Asgard. (They also lead people who have died from other causes other than violent death on the path to Valhalla. They are psycho pomps.) Once there, they serve mead to those who have become Einherjar.
Often seen as riding wild wolves, or in some accounts soaring though the air like a raven scavenging for souls; Valkyries are beautiful shieldmaidens armed with helmets and spears. Although beautiful, they are war-like. Names of Valkyries often mean 'raging', 'shrieking', 'screaming', etc...
If you see a Valkyrie, it means only one thing, you're going to die.