What is Melkor?
1.
The villain of
Melkor was the name of
But I digress.
As Iluvatar and the other Ainur sang Ea (Ea comprised the heavenlies and Arda, aka, Middle-earth) into existance, Melkor decided to sing his own songs, creating some of the more unpleasant things in Arda. He also had a following among the Maiar, the most loyal of these being
When Arda's creation was basically completed, some of the Ainur descended there to live and expand the creation. Melkor was one of them, but spent most of his time marring and distorting the creations of his heavenly brethren.
Melkor eventually established his base in northern Arda and named it Utumno. From his evil lair, Melkor accomplished an impressive resume of evil deeds, including the destruction and/or corruption of the two Lamps, the Spring of Arda, the Two Trees, and the theft of the Silmarils. He also bred all the monsters of Arda, including Balrogs, dragons, trolls, and orcs (Elves corrupted through torture). He spread enough lies, hatred, and other evils and poisons throughout Arda to corrupt it permanently (though not thoroughly).
Melkor was captured and cast into the Void during the Great Battle, before the Third Age. (I'm not sure exactly when.) Sauron continued the spreading of evil in Arda after his master's defeat.
Melkor's story is long and complicated, told mostly in the book The
Feanor, a Valar, changed Melkor's name to Morgoth after Melkor poisoned the Two Trees and stole the Silmarils.
See
2.
The evil first Dark Lord of Middle Earth. He was the most powerful of the ainur race and in the Valar division. He was more powerful than Sauron, by loads, as Sauron was only of the Maiar, though among the most powerful. Eventually Melkor was known as Morgoth, he anihilated Elves and Men but Valar sealed him away until Dagor Dagorath
Big Baddie in all Middle-Earth
3.
First evil overlord in LotR, Melkor, a.k.a.
Melkor was the Great Evil that Aragorn mentioned.