Dark Elf

In J. R. R. Tolkien's Middle-earth, the Moriquendi -- the Elves of Darkness -- are, in essence, the Elves that did not cross over the sea and behold the light of the Two Trees in Valinor. They lingered on the shores of Middle-earth or, indeed, never passed the Blue Mountains on the east of Beleriand or the Misty Mountains further to the east.

"Those Elves the Calaquendi call the Umanyar, since they came never to the land of Aman and the Blessed Realm; but the Umanyar and the Avari alike they call the Moriquendi, Elves of the Darkness, for they never beheld the Light that was before the Sun and Moon."

Other dark elves from other fictional created worlds are the very different Drow elves from Dungeons & Dragons worlds of Greyhawk and the Forgotten Realms.