Dark Elf is an epithet given to drow in AD&D's Forgotten Realms and Greyhawk settings. Dark Elf is simply a 'clean' translation of the Scandinavian expression 'svart alf' - literally, 'black elf'. In the Dragonlance setting, the name is applied to Dalamar, an elf who became a mage of the black robes. Various elvish factions in the Silmarillion could bear the name, and I'll mention them by name when I take the time to get my copy of the book out.