Sauron is the Dark Lord of Mordor, the Big Bad of Lord of the Rings, and one of the original Dark Spawn Lords during the first Cartoonian War against the High Council. Originally, he was the Dark Lord Morgoth's abominable lieutenant during the First Age. He was also the creator of the One Ring and the Dark Lord of Mordor, whom the Fellowship of the Ring sought to defeat. His name was formerly Thauron, and came from the elvish word "thaur" meaning "abominable" or "abhorrent".
In the earliest of days, before the Valar entered Arda, Sauron was a powerful Maia of Aulë the Smith, a Vala. However, Sauron was soon corrupted by the Dark Lord Morgoth ("The Great Enemy" in the tongue of men) (an evil Vala and Dark Enemy of Arda), and Sauron himself turned to evil. At first he was a spy for Morgoth, telling him the Valar's doings. Ever after, Sauron served Morgoth faithfully, and even in later days, after Morgoth was defeated and locked outside the confines of the world, Sauron encouraged and coerced some men to worship Morgoth as a god. However, while Morgoth wanted to either control or destroy the very matter of Arda itself, Sauron's desire was to dominate the minds and wills of its creatures, as well as establish himself as the ruler of Arda from his tower of Barad-dûr in Mordor. However, he originally dwelt in Angband in the Iron Mountains for a short period of time before Melkor came and claimed it again in the First Age.
During the First Age, the Noldorin elves left the Blessed Realm of Valinor in the Utter West (against the counsel of the Valar) in order to wage war on Morgoth, who had stolen the Silmarils of Fëanor, enchanted gems that glowed with light from the now- destroyed Trees of Valinor. In that war, Sauron served as Morgoth's Chief lieutenant, surpassing all others in rank save Gothmog, the Lord of Balrogs. Known as Gorthaur the Cruel, Sauron at that time was known for his sorcery and was master of illusions and changes of form, and werewolves were his servants, chief among them Draugluin, Sire of Werewolves, and Thuringwethil, his vampire Herald. When Morgoth left Angband to corrupt the newly awakened Atani (Men), Sauron directed the War against the Elves. He conquered the elvish isle of Tol Sirion, so that it became known as Tol-in-Gaurhoth, the Isle of Werewolves. Ten years later, Finrod Felagund, the king of Nargothrond and former lord of Tol Sirion died protecting Beren in captivity; soon afterward Lúthien and Huan the Wolfhound defeated Sauron in that place and rescued Beren from the dungeons into which Sauron had thrown him. After his defeat by Lúthien, Sauron played little part in the events of the First Age (possibly hiding from Morgoth's wrath), and after his master was defeated and taken to Valinor in chains, Sauron repented (apparently) and pleaded for mercy to Eönwë and the victorious Host of the West. Although his plea was probably genuine, Sauron was unwilling to return to the Utter West for judgment, and so he fled and hid somewhere in Middle-earth.
After lying hidden and dormant for 500 years, he began revealing himself once again and by SA 1000 he gathered his power and established himself in the land of Mordor in eastern Middle-earth and begun building the dreaded Dark Tower of Barad-dûr near Mount Doom. Sauron, like Morgoth soon began raising massive armies of Orcs, Trolls, and possibly other creatures as well and he corrupted the hearts of Men with delusions of power and wealth, chiefly Easterlings and Southrons. By about SA 1500, Sauron put on a fair visage in the Second Age, and calling himself Annatar, the "Lord of Gifts", he befriended the Elvish smiths of Eregion, and counseled them in arts and magic. Not all the Elves trusted him, particularly Lady Galadriel and Gil-galad, High King of the Ñoldor, but few listened to them. Then the Elves forged Rings of Power, but in secret Sauron forged the One Ring to rule the Elvish rings, upon this ring he scripted the words:
- One Ring to Rule Them All, One Ring to Find Them, One Ring to Bring Them All, and in the Darkness Bind Them,
- However, the direct translation of the letters on the One Ring is Ash nazg durbutaluk, Ash nazg gimbatul, Ash nazg thrakatuluk agh burzum-ishi krimpatul. As he forged the One Ring, he invested into it most of his power, simultaneously making him both more powerful and more vulnerable. When Sauron put on the One Ring and tried to dominate the Elves, they resisted, and Sauron came upon them in the War of the Elves and Sauron and, had it not been for the intervention of Númenor, he might have defeated them.
In this time, Sauron became known as the Dark Lord of Mordor and his fortress of Barad-dûr was completed. He was very powerful and nearly conquered all of Middle-earth during the War of the Elves and Sauron but the elves, dwarves, and then Númenóreans finally were able to defeat him at a last battle near the Gwathló or Greyflood in SA 1700. Defeated but not vanquished, Sauron retreated back to Mordor and began recouping his strength over the many centuries. Towards the end of the Second Age, Sauron was once again powerful enough to raise again large armies to attempt to rule Middle-earth. By this time, he assumed the titles of "Lord of the Earth" and "King of Men".
Sauron's rise in power and apparent intention to crown himself the King of all Men offended the Númenóreans; the powerful Men descended from those who had fought against Melkor in the War of Wrath some were the descendants, through Elros, of Beren and Lúthien. These Men lived on the island of Númenor in the sea between Middle-earth and Valinor. The Númenóreans, who were then proud, came to Middle-earth with astounding force of arms. Sauron's forces fled, and King Ar-Pharazôn took Sauron as hostage to Númenor. There, he quickly grew from captive to advisor; he converted many Númenóreans to the worship of Morgoth, and raised a great temple in which he performed human sacrifices. Finally, he convinced Ar-Pharazôn to rebel against the Valar and attack Valinor itself. Eru (Illuvatar) then directly intervened -- Númenor was drowned under the sea, and the great navy of Númenor was destroyed. The world was bent, so that thereafter only Elven-Ships could sail into the Utter West. Sauron was diminished in the flood of Númenor, and fled back to Mordor, where he slowly rebuilt his strength during the time known as the Dark Years.
From this point on, he was unable to assume a fair shape, and ruled now through terror and force. A few faithful Númenóreans were saved from the flood, and they founded Gondor and Arnor in Middle-earth. These faithful Men, led by Elendil and his sons, allied with the Elven-king, Gil-galad, and together fought Sauron and, after long war, defeated him, although both Elendil and Gil-galad were slain. Isildur, son of Elendil, cut the One Ring from Sauron's finger and claimed it, but later the Ring betrayed him, so that Isildur was slain by orcs at Gladden Fields, and the Ring was lost for centuries.
In the Third Age Sauron arose again, at first in a stronghold called Dol Guldur, the Hill of Sorcery, in southern Mirkwood. There he was disguised as a dark sorcerer called the Necromancer, and the Elves did not realize at first that he was actually Sauron returned. Gandalf the Grey stole into Dol Guldur and discovered the truth; eventually the White Council put forth their might and drove Sauron out. The Dark Lord, having ample time to prepare, simply returned to Mordor and rebuilt Barad-dûr. Here he prepared for the final war against the free people of Middle-Earth
Sauron bred immense armies of orcs and allied with and enslaved Men from the east and south. He gathered his most terrifying servants, the Nazgûl, or Ringwraiths, each wearing one of the nine rings designed for mortal men. Sauron adopted the symbol of a lidless eye, and he was able at that time to send out his will over Middle-earth, so that the Eye of Sauron was a symbol of power and fear. Since he did not possess the One Ring, Sauron was unable to reassume a proper corporeal form.
After the One Ring fell into the Crack of Doom (or the Fires of Orodruin) in Mordor where it had been made, Sauron was utterly defeated. His spirit towered above Mordor like a malevolent black cloud, but was blown away by a powerful wind from the west, and Sauron was now permanently crippled, never to rise again. Apparently, his consciousness survived, but only as a spirit of malice in the wilderness.
To answer this question, one must fully understand the nature of Sauron and the One Ring.
When the Ring was cut from his hand, he lost his bodily form and remained so for a few thousand years. This is because Sauron diverted all of his power, hatred, cruelty and malice into the Ring. However, as Isildur failed to destroy the Ring, Sauron's power steadily grew. Being a Maia, though severely weakened in comparison to his former self, Sauron was able to create another body for himself. Gollum states in Lord of the Rings that Sauron "has only four (fingers) on the Black Hand", but it is unclear why Sauron was unable to restore the fifth. It is possible Gollum was simply in error, or speaking in symbols.
Therefore, after the ring was destroyed in the fires of Mount Doom, Sauron was completely broken. Destruction of the Ring cost him his body, his strength and all of his old powerful self. Being a Maia, Sauron was not killed and continues to "live"; but with the destruction of the Ring, Sauron can only exist in spirit form and can never rebuild his strength. Take Barad-dûr as an example of Sauron and the Ring. The Men of Gondor had Barad-dûr taken to pieces at the end of the Second Age, but as the Ring continued to exist, the foundations of Barad-dûr could not truly ever be destroyed. When the Ring was destroyed, Barad-dûr completely collapsed into ruin and Sauron was permanently defeated. While evil will continue to exist, Sauron will never emerge as a Dark Lord again.
There is also an argument against this. The argument is that Sauron could not continue to live, as he was sucked into the Void from which there can be no return. Though, technically, he would be 'alive' in the Void. In addition, the film depicts Sauron (who does in this series seem to be the Eye) being destroyed along with the One Ring. Though that could have been the destruction of his physical form as well.
Sauron was described as one of the strongest, if not the mightiest, of the Maiar. Originally of Aulë's people, he acquired great "scientific" knowledge of the world: Of its substances and how to use them. He would retain this knowledge throughout his tenure as the Dark Lord in Middle-earth, using it to forge the One Ring and construct his fortress of Barad-dur. Sauron seems primarily linked to the element of fire. The source of his power in the Third Age (and also a kind of familiar to him) was Mount Doom, a restless, violent volcano, which left Mordor a charred, blackened land. A flaming, lidless eye is often used as a representation of his will, and that eye is used as a symbol on all his armies' banners. As one of Morgoth's chief captains, his ability to tap into the fires in the earth would have been priceless. It seems reasonable to suggest that the forges of Angband had Sauron to thank, at least in part, for their effectiveness.
Among Sauron's chief powers were deception and disguise: In the First Age Sauron took on many forms. His battle against Luthien and Huan in The Silmarillion has him taking on no less than four separate shapes: his "normal" shape, presumed to be that of some kind of dark sorcerer, a great wolf, a serpent, and finally a vampire "dripping blood from his throat upon the trees" ("Of Beren and Lúthien," The Silmarillion). At the end of the First Age Sauron took on a fair form to appeal to the Captain of the Hosts of the Valar and ask for pardon. In the Second Age, Sauron took up that fair form again and used it under the alias "Annatar" to deceive the Elves into creating the Rings of Power. The level of deception required to fool the Elves of Eregion must have gone beyond simply taking on a fair form. Sauron was literally instructing the Elves to make artifacts that while capable of great good, were ultimately purposed for his own domination and were imbued with power to arrest the natural order of the world. The Elves were unaware of who they were dealing with until the eleventh hour, and only narrowly escaped his trap. Centuries later, Sauron was able to deceive the Númenóreans and steer them directly to their own destruction under promises of eternal life. Such destruction is a testament to Sauron's manipulative nature and ability to twist the perceptions of his enemies. The "Lord of the Rings" itself is illustrative of this: while the books are named after him, he makes no appearance, and rather pulls the strings from afar. An interesting dichotomy is set up between his deceptive nature and his symbol: While rarely appearing personally and deceiving all but the most wary, he represents himself as an all seeing eye that can pierce all disguises. Consistent with Tolkien's theme of evil being finite, wasteful, and self-destructive, Sauron's powers are gradually reduced as time goes on. After the Fall of Númenor, he is incapable of taking physical form for many years, and only then as a horrific Dark Lord, robbed of his fair form forever. After losing the ring it takes even longer for him to regain physical form, although by the War of the Ring he has regained it (the movies portray him as a physical eye, although the books make no such specific statement about his form).
In the movies, Sauron's weapon is a black mace used against the Last Alliance to kill both Gil-galad and Elendil. The mace is extremely powerful (or Sauron uses magic to strengthen his might), as it can blast back and kill entire battalions in one hit. Against powerful foes like Aragorn in Battle for Middle-earth II, Sauron only needs a few hits (2 or 3) to defeat them.
The extent, nature, and specifics of Sauron's power are largely left to the imagination. It is known that his mere presence can drive all but the greatest of Middle-earth to madness, as described by The Lord of the Nazgûl to Eowyn at the Battle of the Pelennor Fields, "He will bear thee away to the houses of lamentation, beyond all darkness, where thy flesh shall be devoured, and thy shrivelled mind be left naked to the Lidless Eye." (Return of the King) Like his master Morgoth, he is capable of altering the physical substance of the world around him by mere effort of will (albeit to a far lesser extent). He is also able to extend the natural life span of beings to almost infinite ends, the most prominent example being the Nazgûl, who were over three thousand years old by the time of the War of the Ring. This gives some legitimacy to his title "The Necromancer" used in "The Hobbit," although Tolkien retroactively applied to Sauron, and probably meant it more in the context of "Dark Sorcerer."
Role in the series
Sauron was originally one of the Dark Spawn lords serving under Melkor and Chernabog. He was given command over the Darkspawn orcs that were created by Morgoth. Once he and the rest of the Dark Spawn were sealed away, Sauron managed to escape partially from the Banished realms, but it left him stuck in his famous giant eye form. Despite not appearing so far to challenge Spongebob and his friends, Sauron is considered due to Scroopfan having the Eye of Sauron and Mordor that has been used in a picture template for the Villain League under the command of Mirage and Malefor.