And In All The Deeds of Melkor the Morgoth

Name: Sauron, "abhorred". Originally, his name was Mairon ("admirable") and even after others began calling him Sauron, he referred to himself as Tar-Mairon until after the Fall of Numenor.

Age: Older than the dirt of Arda. Sauron is a Maia, a sort of lesser god created by Eru in the Timeless Halls; he existed before Arda was created.

Appearance: Initially, like the Ainur, the Maiar could wield any form; like other Maia and the Ainu, Sauron could make himself Man, Elven, werewolf, whatever. His spirit could not be destroyed, though the physical body could be. Tolkien doesn't describe just what Sauron looked like very much, beyond his time in Numenor when he's disguised and going by the name Annatar; "as a man, or one in man's shape, but greater than any even of the race of Númenor in stature... And it seemed to men that Sauron was great, though they feared the light of his eyes. To many he appeared fair, to others terrible; but to some evil.” Beyond that, Sauron's eyes tend to get much more attention than the rest of him, which are described as yellow as a cat's and lined with fire by the time Frodo's seeing his eye through Galadriel's mirror in the Third Age.

Things we do know are that he was fair before joining Melkor outright at which point his form turned sinister, and that even when his form turned terrible after the Fall of Numenor he still had a stature slightly greater than Men. By the end of the Second and into the Third Age, his physical form was that of a terrible dark lord, ”an image of malice and hatred made visible”with blackened hands that burned like fire, hot enough to kill Gil-galad. Presumably, his entire body was blackened by fire and heat. Upon seeing his hand, Gollum recalls that he only had four fingers, thanks to Isildur cutting one off to take the One Ring; like Morgoth before him, Sauron apparently wasn’t able to heal the wound. And all the while, he had daunting eyes.

Beyond physical forms, he had an aura that gave away his malevolence; he’s said to have a ”dreadful prescence” that could bend all but the strongest wills.

For before the period before the Fall of Numenor, when he could still hold fair form, I tend to go by Phobs’ design, with the adjustment of having more melanin. Red hair, eyes like smithing fires, and dark skin.

Personality: There’s a couple big things about Sauron to know; Melkor, order, and (as pointed out by Elrond) nothing is evil in the beginning, not even Sauron.

To begin with, Sauron was a maia under Aule, the smith. This is a big part of why he has so much knowledge on what makes Arda and how to craft it; he was once one of the greatest and mightiest of the maia, to the point he still held an important place in the lore of Aule’s people. His virtue and strength? A love of order and distaste for anything wasteful.

This ended up being kind of a problem when he became attracted to Melkor’s power, because with that power Melkor could enforce the order Sauron wanted so much. Sauron is described as an evil only slightly lesser than Melkor, simply because he never actually thinks for himself here; when Melkor is imprisoned in the Halls of Mandos, Sauron doesn’t make an attempt to take over, when Melkor is cast into the void, Sauron rises up like a shadow of Melkor and walks the same path down into the void. And he kind of loses it, but details. The fact remains he is amazingly loyal to Melkor the Morgoth, even as the Ainur consistently destroys the order Sauron strives to create.

According to Tolkien, Sauron initially took into consideration the well-being of other inhabitants of Arda, but went beyond human tyrants in pride and lust for domination thanks to being a maia (and doubtlessly his need to impose order under one will). As far as his servants were concerned, Sauron was a God-King for three reasons: he had fallen with Morgoth and served as his best lieutenant (many of Morgoth’s schemes would have surely failed without Sauron’s mind), though Sauron asked for pardon from Eonwe he didn’t return to Valinor and instead fled and remained in Arda, and lastly his pride as he realized how greatly his knowledge was admired.

For example, as stated previously Sauron had great scientific knowledge of Arda and its resources, even able to tap into the fires of the planet itself, as well as using this knowledge to construct both the One Ring and Barad-dur, which in the films is depicted to be 5,000 feet tall. Like Melkor, Sauron was capable of altering the physical substance of the world through sheer will.

Perhaps Sauron’s greatest power, however, lies in his ability to deceive. Which makes the fact his symbol all know him for is the all-seeing, lidless eye a little ironic. It’s said this eye could pierce all disguises, that Sauron’s perception could see all (and in the movie, quite literally, as the eye scans Arda like a search light). Sauron could deceive all but the most wary, which were few and far between; he had even been able to deceive all of Valinor, as well as Numenor and the elves under his guise of Annatar.

Before losing his ability to change forms, Sauron was a shapeshifter; his usual form, a great wolf, a serpent, a vampire dripping blood from its neck thanks to Huan’s bite. These are but a couple examples. It was in the Second Age that Sauron deceived the elves as Annatar, the lord of gifts. He taught them how to create the rings of power which he planned to use to arrest the natural order of the world and bend it to his own will, and the elves had been unaware of Annatar’s true identity until it was nearly too late, and they narrowly escaped the trap. With promises of eternal life, human sacrifice became common place on Numenor as they worshipped Melkor, and Numenor was sunk beneath the waves, and Sauron with it. The last part wasn’t really planned by him, but he deceived the island nation enough that he still steered them to their own destruction. Sauron’s manipulative nature and ability to twist the perception of others is used frighteningly well. Before either of these, though, he deceived the Valar; the Ainur and Maiar who descended to shape middle earth. After joining Melkor's side, Sauron gave the Ainu information regarding the Valar and their plans, and was not suspected to be the traitor as he even accompanied them to Valinor, though it wasn't long after this the truth came out simply because he left and joined Melkor outright.

Beyond this, though, Tolkien doesn’t give the character much of a personality. Sauron serves to define others, not to hold the spotlight himself; he rarely shows himself even after gaining a physical form again, and much of what is known of him is inferred from his interactions with other characters.

He is cruel, and wise. He is a liar, and cunning. He is proud, and patient.  He’s obsessive about order—even rejecting Melkor in the beginning due to the chaos the other introduces. He’s also startlingly loyal to his side; there is no good or evil in his morals, simply his side and those against him, and as long as Melkor walked Sauron never served his own purposes, even when Melkor’s went directly against what Sauron wanted in the end; perhaps he believed once the races were dominated he could have the order he wanted. He’s honest occasionally, in a twisted way. He promised he’d reunite Barahir with his wife if he gave Sauron the information he wished for, and Sauron kept his word; by killing Barahir to reunite him with his dead wife. He makes an attempt to right the wrongs done to Arda and even asks forgiveness from Eonwe, only to recoil from Valinor and to come to hate the Firstborn and Secondborn because they wouldn’t simply give in to him.