Title of EÃ¶l of Nan Elmoth.
When Melian set her Girdle around the land of Doriath, Thingol's kinsman EÃ¶l left that land, and dwelt instead in the forest of Nan Elmoth. Living under the dark shadows of that ancient forest, and preferring the night to the day, he came to be widely known as the Dark Elf.
EÃ¶l's epithet was no doubt influenced by the fact that the Sindarin Elves to whom he belonged were of the Moriquendi, the Dark Elves who had never seen the light of the Two Trees of Valinor.
In the language of Aman all Elves that did not cross the Great Sea were Dark Elves (Moriquendi), and the term is sometimes used thus; when Caranthir called Thingol a Dark Elf it was intended opprobriously, and was especially so, since Thingol had been to Aman 'and was not accounted among the Moriquendi'. But in the period of the Exile of the Noldor it was often used of the Elves of Middle-earth other than the Noldor and the Sindar, and is then virtually equivalent to Avari. Different again is the title Dark Elf of the Sindarin Elf EÃ¶l; but in the Quenta Silmarillion, Turgon no doubt meant that EÃ¶l was of the Moriquendi.
Elves who never saw the Two Trees.
The Moriquendi, those Elves who refused the summons of the Valar to Valinor, or fell away on the Great Journey, and never saw the light of the Two Trees.
The Dark Elves are often equated with the Avari, who refused the summons of the Valar and remained in the darkness of Middle-earth. This is not strictly correct; 'Dark Elves' also include those such as the Nandor and Sindar who started the Great Journey to Valinor, but never came there.