> The Silmarillion
He Who Arises in Might
Morgoth Bauglir, the Dark Lord, the Foe of the Valar, the Great Enemy, the Evil of the North, the Black Hand, the Master of Lies, the Hunter, the Lord of Darkness, the Lord of All, the King of the World
Melkor is the original name of Morgoth which means "He who arises in Might." He was the greatest of the Ainur and wielded the greatest power and knowledge. Especially interested in thing of substance and crafts like Aulë, he desired to bring things of his own design into being. He searched through the Abyss for the Flame Imperishable and during these long quests he started to have thoughts different from the rest of the Ainur and their Music.
When Eä was created and some of the Ainur entered in, Melkor was among them. His desire to create things of his own led him to intense jealousy and finally he claimed Arda as his own. When the Valar oppossed and thwarted him in his plan, he bent himself on marring their work and corrupting the lesser Maiar to his service. To serve this end he took on an image of majestic terror. Eventually Melkor was defeated when Tulkas entered Arda and overcame him in battle.
When the Valar set back to healing Arda, Melkor secretly came back and built his stronghold of Utumno in the North. Crippled by his defeat, he now lost the power to create new things and had been reduced to corrupting the Light1. He attacked Arda yet again with a blight of plague, awakening the Valar to his presence. He destroyed the Lamps of the World before the Valar could retaliate and retreated back to Utumno. During this time the Valar yet again tried to heal Arda and created the Two Trees to serve as Light in the world.
When the Elves awoke he appeared to them as a dark rider, seeking to make them fear the Valar and captured a few of them which he later corrupted and bred into Orcs. This was a breaking point for the Valar. In concern for the safety of the Children of Ilúvatar, they waged the Battle of the Powers against Melkor and carried him to Valinor in chains. Here he was imprisoned for three ages, but a shadow remained on Middle-Earth.
After three ages in chains, Melkor put on a fair form and decieved Manwë, who had no understanding of Evil, to release him. He was forced to remain in Valimar and there he grew covetous of the Silmarils of Fëanor. When the Noldor grew to distust him, he fled from Valinor. Here he permanently assumed the shape of the Dark Lord again and went to the far South, where he gained the aid of Ungoliant. The two plotted to take the Silmarils and destroy Valinor. They accomplished this and quickly fled to Middle-Earth where they argued over the spoils. Ungoliant, who desired the Silmarils to quench her unsatiable hunger, attacked Melkor. Melkor gave a great cry, which summoned his Balrogs who saved their master and brought him to Angband.
There, Melkor defended the Silmarils from the Noldor who had returned to Middle-Earth. During this time, the Edain (Men) had awakened and he also corrupted a portion of them to his service. To aid in the fight against Melkor, the Valar made the Sun and the Moon from the last fruits of the Two Trees which Ungoliant has destroyed. Melkor assailed the Moon and tried to bring it down, but was unsuccessful. At last the Noldor managed to trap him in his stronghold of Angband for over four hundered years, during which Melkor increased his power and forces. He broke the seige with the Dagor Bragollach, and slowly destroyed all of Beleriand.
Eventually, Melkor was defeated, but not without terrible losses. He had slain Finwë, at least indirectly caused the deaths of many of the Kings and Princes of the Noldor and Edain, and left Arda Marred. He was cast out of Eä and into the Void permanently, but his shadow never left.
In person he was not courageous and walked with a limp after he recieved eight great wounds from Fingolfin and Thorondor. His hands were burnt black from holding the Silmarils and he was in constant pain.