
There he took up again his great Ring in Barad-dûr, and dwelt there, dark and silent, until he wrought himself a new guise, an image of malice and hatred made visible and the Eye of Sauron the Terrible few could endure.” “But Sauron was not of mortal flesh, and though he was robbed now of that shape in which he had wrought so great an evil, so that he could never again appear fair to the eyes of Men, yet his spirit arose out of the deep and passed as a shadow and a black wind over the sea, and came back to Middle-earth and to Mordor that was his home. Sauron was killed by the Downfall of Númenór, but his spirit returned to Middle-earth and to his land of Mordor, carrying the One Ring with it.

Sauron, still in his fair form, was taken as a prisoner to Númenór, where he corrupted the king and the people into worshiping Morgoth. After millennia of history, Ar-Pharazôn the Golden, King of Númenór, came to Middle-earth with a vast army. Sauron used a fair looking form when he taught the Elven smiths how to make rings of power, but Sauron secretly made the One Ring to rule them all. Sauron fled and hid for a long time during the Second Age, before seeking to gather evil creatures and conquer Middle-Earth. The powers unleashed by the Host of Valinor against Angband were so great that the land of Beleriand sank beneath the sea in ruin. The creatures of Morgoth, orcs, and trolls, and dragons, and balrogs, and the evil Men who allied with them, were all killed, or fled in terror. Ancalagon the Black fell upon the towers of Thangordrim and ruined them, and Morgoth's realm of Angband was destroyed. The forces of Morgoth were defeated the War of Wraith and the Great Battle at the end of the First Age. But Huan won, and Sauron surrendered the fortress to Lúthien, and then turned into a giant vampire bat and flew away. The tale of Lúthien during the First Age of the Sun tells how when Sauron had Beren imprisoned in a fortress, Lúthien and Huan the Hound came to rescue him, and Sauron turned himself into a werewolf to fight Huan, since it was foretold that Huan would only be killed by the greatest werewolf ever. But an Ainu could make any form of body it wanted to. The normal form of body for an Ainu to make resembled a human body, but usually larger. However, when evil Ainur inhabited the same bodies for decades, and centuries, and millennia, their ability to create new bodies weakened or even vanished. The Ainur were spirits and had no physical bodies, but could make physical bodies for themselves as easily as humans can put on clothing.

Sauron was the greatest of the Ainur who were corrupted by Morgoth, the first Dark Lord, and was his greatest servant during the countless millennia of the Eldar Days before the Sun and the Moon were created.

Many of the Ainur entered the world when it was made. Sauron was an Ainu, a sort of angelic spirit that existed long before the world was created.
