However, in the Return of the King, Gandalf explains that when the One Ring is vanquished, Sauron will be "maimed forever, becoming a mere spirit of Malice that gnaws itself in the shadows, but cannot again grow or take shape.
The Fourth Age began once Sauron was vanquished and the One Ring destroyed. The Shire and the kingdoms of Arnor and Gondor were restored. It marked the ascent of Men and the final diminishing of the Elves. Gandalf, Elrond, Galadriel, Bilbo and Frodo sailed for the Undying Lands, as had most Elves on Middle-earth.
Finally Sauron came out to fight Elendil and Gil-galad face to face. When Elendil fell, his sword Narsil broke beneath him. Isildur took up the hilt-shard of Narsil and cut the One Ring from Sauron's hand, vanquishing Sauron.
The White Wizard's fate was very similar to the Dark Lord's. In the novel, after Wormtongue killed Saruman, the hobbits saw his spirit rise from his body, much like Sauron's. However, Saruman's spirit was smaller, and it resembled a gray cloud instead of a black shadow.
In both the movie and the book versions, Saruman was killed by a mortal man with a simple knife. But that still begs the question of how he could be killed at all. In order to answer that, one must understand his station on Middle-earth. Like Gandalf he was a Maia, which meant that he was immortal.
Sauron wasn't allowed to return and reincarnate himself, because: He never went to the Valar, his spirit wandered free and waited until he got enough power to re-create his form.
"So I think in his pitch to Galadriel, it cannot mean that he loves her or that there's any kind of romantic relationship. There should be no ambiguity around the fact that Sauron is evil — he's terrible, and he's using Galadriel to enhance his power."
Bloodlines are very important in Tolkien's stories, and it makes a lot of sense that Sauron would fear the great-grandson of the man who cut off his hand. Aragorn carried the blood of Numenor with him. His genetic connection to the heroes of the Second Age established him as a dangerous opponent of Sauron.
After Sauron's defeat, Aragorn and his army killed the remaining Orcs in Mordor. It can be assumed that any Orcs in the Lonely Mountain would have also escaped once they got to know about their master's downfall.
Eventually, Morgoth was bound in chains by the Valar and thrown into the Void, leaving the permanent damage his evils had done, and his former lieutenant Sauron, to trouble the world. One day, according to a prophecy, Morgoth will rise again in great wrath, but he will be destroyed in the Dagor Dagorath.
The in-world explanation, of course, is that having infused so much of his power into the One Ring when it was forged, that power evaporated when the ring was destroyed, and Sauron lost his power to exist in the world.
Sauron was originally a shape-shifting fallen angel and could take on various forms, including a vampire and a werewolf. Sauron's final form was terrifying and demonic, reflecting his own hate and evil, and he did not wear armor in the books.
After lying hidden and increasing his power in secret, in S.A. 1200 Sauron put on a fair visage, calling himself Annatar, the Lord of Gifts, an emissary from the Valar.
When Halbrand and Galadriel captured Adar, Adar seemed not to recognize Halbrand as Sauron. Adar also claimed to have killed Sauron after watching Sauron experiment on the orcs, whom Adar sees as his children. It's possible Adar was pretending not to recognize Sauron as part of a ruse.
Melkor is the most powerful of the Valar but he turns to darkness and is renamed Morgoth, the primary antagonist of Arda. All evil in the world of Middle-earth ultimately stems from him. One of the Maiar of Aulë betrays his kind and becomes Morgoth's principal lieutenant and successor, Sauron.
Morgoth, the first to reign terror upon Middle-earth, was more powerful than Sauron and commanded an army of dragons and Balrogs. While both Morgoth and Sauron were cunning, Morgoth's rule and terror lasted longer and his corruption spread further, making him more formidable in the Lord of the Rings universe.
In his notes, Tolkien remarks that Sauron saw Galadriel as his equal. Add that to the fact that she's untrusting of Sauron (yes, even when he's in his Annatar guise) and an unwavering, single-minded force, and it's more likely than not that Sauron feared Galadriel — or the potential she held to upend his plans.
After trying and failing to murder Sauron to save Middle Earth in the final episode, Season 2 of The Rings of Power could see Galadriel blinded by rage at Sauron's betrayal and deception. One thing is now certain; the friends, and even potential lovers, have become sworn enemies.
This was how Halbrand/Sauron actor Charlie Vickers played the part, saying he believed the proposition to become his queen came "from a place of selfishness." Regardless, Galadriel denied the proposal. However, her answer did not come without hesitancy -- which was exactly why Celeborn needed to be out of the picture.
As an immortal Maiar, Gandalf's soul traveled to the Timeless Halls after his death, where the god of The Lord of the Rings dwelled, Eru Ilúvatar. Recognizing that Middle-earth still needed the White Wizard and that Saruman had abandoned the role, Eru reincarnated Olórin's soul into the body of Gandalf the White.
Of course, once the Gray Wizard arrived in Isengard to ask Saruman about the One Ring, he discovered that his "old friend" had turned from the ways of good, instead deciding to serve Sauron in an attempt to claim power (and even the One Ring) for himself.
When Aragorn, Legolas, and Gimli mistake Gandalf for Saruman in The Two Towers, he tells them: “Indeed I am Saruman, one might almost say, Saruman as he should have been.” While still tasked to advise and counsel rather than apply force, Gandalf as the White had more power to “reveal” his true strength.
