Melkor

Melkor ("He who arises in might"), later known predominantly as Morgoth ("Black Foe of the World"), was the first Dark Lord, and the primordial source of evil in Eä.

Originally the most powerful of the Ainur created by Eru Ilúvatar, Melkor rebelled against his creator out of pride and sought to corrupt Arda. After committing many evils in the First Age, such as the theft of the Silmarils, which resulted in his name Morgoth, and the destruction of the Two Lamps and the Two Trees of Valinor, Morgoth was defeated by the Host of Valinor in the War of Wrath. As punishment he was cast out of Arda into the Void, though it was prophesied he would one day return.