Melkor

Morgoth Bauglir was once a Vala named Melkor in Middle-Earth.

Biography
Morgoth was the first Dark Lord and, even as an Ainu, he was filled with pride and malice, bringing a discord to the Great Music of the Ainur.

During the creation and shaping of Arda, Morgoth thwarted it and made it marred and imperfect, and while the Valar started to build their kingdom of Almaren Morgoth corrupted many of the Maiar. He then took them into the north of Middle-earth, and formed a alliance called The Dark Powers, and created rival kingdoms to Almaren; that of Utumno and that of Angband and Thangorodrim.

From these cities Morgoth waged five massive wars against the Valar, flattened Almaren, and destroyed the Great Lamps and the Trees of the Valar. Before this, The Dark Lord had had two forms; fair (Melkor), and foul (Morgoth). But now he took on the foul, evil form which the Elves called 'Morgoth'. Morgoth was as tall as a high tower, wore an iron crown and a long black cloak over his night-black armour (possibly mithril), and carried with him a long sword, a spear or halberd, and the dark warhammer called Grond, The Hammer of the Underworld. Grond was also the name for the battering ram used by the Witch-King to knock down the gates of Minas Tirith in ROTK

During the War of the Powers, Morgoth had been captured and chained, and for some years Middle-earth was allowed to prosper. But at last Morgoth was brought before the Valar to be judged. To the Valar he seemed to have changed, and mellowed so Manwë, Lord of the Valar, that he ordered his chains removed. But they were all deceived, and Morgoth continued to wage war against them, destroying the Trees of the Valar with his ally Ungoliant (the first giant spider of Middle-earth) and stealing the gemstones known as the Silmarils.

Another war began, The War of the Great Jewels, in which Fëanor (the maker of the Silmarils) led armies against Morgoth. This war lasted through the whole of the First Age of the Sun. Finally, in the War of Wrath, Angband was destroyed and, though Morgoth tried to call up more and more beasts of the shadows to aid him, he was sent into the Void by the Valar. Although he could not escape and return to conquer Middle-earth, he left his lieutenant and ally behind, Sauron. Morgoth's terrible power would live on yet through Sauron, as is described in The Lord of the Rings. It is prophesied that Morgoth will return for the final battle between light and darkness, the Dagor Dagorath, and will suffer his ultimate and final defeat.

There is a certain parallel between the stories of Morgoth and of Lucifer in Christian theology. They both tell of beings of great power created by an omnipotent deity, both being the greatest (Lucifer was regarded as being "brightest of them all"). Both stories tell of the being's fall from grace, and his subsequent war on the forces of his creator. As Tolkien was a Catholic, this parallel may well be intentional.

Of The Cursing of Hurin
Morgoth is also well known for the imprisonment of Hurin of the House of Hador during the Battle of Unnumbered tears. In the last hours of the battle Hurin and his kin defended Turgon, for he was the last heir to the throne of Gondolin and of Fingolfin after his brother, Fingon, fell in battle. Turgon narrowly escaped the clutches of the host of orcs due to the valor of Hurin and Huor and their men.

Unfortunately, all but Hurin survived after the onslaught of Morgoth's forces. After slaying 70 orcs, Hurin was bound by Gothmog with his flaming whip and, thus, sent him to Angband. There, after a nightmare of chained torment in Thangorodrim's chambers, Hurin still defied Morgoth Bauglir and rufused to tell him where Gondolin lay. Thus, Morgoth sent Hurin to the top of Haudh-en-Nirnaeth and cast a mighty curse on Hurin and his family:

''Behold! The Shadow of my thought shall lie upon them wherever they go, and my hate shall pursue them to the ends of the world.''

Then continuing his curse, roared:

''But all whom you love my thought shall weigh as a cloud of Doom, and it shall bring them down into darkness and despair. Wherever they go, evil shall arise. Wherever they speak, their words shall bring ill counsel. Whatsoever they do shall turn against them. They shall die without hope, cursing both life and death.''

And so Hurin stayed on Haud-en-Nirnaeth, forever watching his homelands fall under the shadow of Morgoth until he release him. Turin, though valiant and powerful nearly escaped the curse, as feared by Morgoth, but could not leave it. He and his sister perished. And so the curse of Morgoth to the Children of Hurin was fulfilled.

(More is said in The Children of Hurin)