In the Prose Edda, a book written in 1220 by the Icelandic poet Snorri Sturluson, two kinds of elves are described. The Ljósálfar are the light elves, fairer than the sun to look at, dwelling in the heavenly Álfheimr. Then there are the Dökkálfar, dark and swarthy and living underground.
The light and dark elves have been interpreted to be Sturluson taking the Christian stories of angels and demons and incorporating them in to Norse mythology. As the "Elucidarium", an encyclopedia of Christian stories had been translated to Icelandic in the previous century it is believed that this could have served as an inspiration for Sturluson.
While the duality of light and dark, good and evil, are not unique to Christianity, it is still believed the stories of the light and dark elves may be one of few early examples of Christian stories being "paganised".
Campaign: “Curse of Strahd”, Dungeons & Dragons
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