[Morthoron]

I'll have to go with my favorite Moriquendi menace, Eöl. Who else gets the nom de guerre "Dark Elf" (capitalized and singular)? More malovelent and unlike any other Elf in the legendarium, Eöl was both an abductor and murderer, yet accomplished in both the dark arts (weaving webs of deceit to ensnare Aredhel Ar-Feiniel in the woods of Nan Elmoth), and an accomplished smith (forging the enchanted swords Anglachel and Anguirel, and fashioning armor from the meltal Galvorn) -- a wholly despicable yet fascinating character, more so than his son Maeglin, who was cowardly and a traitor.