Sauron was first defeated in the First Age by the great wolfhound Huan and the elf-maiden Lúthien, who forced him to yield his fortress and flee in shame as a vampire, though this wasn't a final death. Later, in the Second Age, his physical form was overthrown by Gil-galad and Elendil, but it was Isildur who cut the One Ring from his hand, ending that reign and leading to his long absence.
Finally, Sauron came out to fight face-to-face, killing Elendil and Gil-galad; Elendil's sword Narsil broke beneath him. Isildur took up the hilt-shard and cut the One Ring from Sauron's hand, vanquishing Sauron.
Sauron was defeated in S.A. 3441 (the final year of the Second Age). He returned (in secret) in T.A. 1000 (so a millennium after his defeat) and sent his servants to start to weaken the Free Peoples in preparation for his return. This took about another millennium.
The war ended when Sauron himself came forth and fought Gil-galad in combat, who was then joined by Elendil. Although they both fell, they managed to defeat Sauron and bring him down. Isildur in the same hour then subsequently cut the One Ring from Sauron's hand, dispersing his spirit.
Why was Sauron afraid of Aragorn potentially possessing the Ring? Gandalf explains it in the Return of the King (during the council after the battle of the Pelennor fields) that Sauron would never think somebody would want to destroy the One Ring.
Elrond chose the fate of the Elves and therefore the choice was presented to his children. The reason why Eldarion and his sisters (the children of Aragorn and Arwen) were born mortal was because Arwen chose mortality and therefore that fate was passed on to the rest of their line.
Saruman first appeared during a fourth phase of writing in a rough narrative outline dated August 1940. Intended to account for Gandalf's absence, it describes how a wizard titled "Saramond the White" or "Saramund the Grey", who has fallen under the influence of Sauron, lures Gandalf to his stronghold and traps him.
He will fight in the Last Battle against the Valar and their allies, but will ultimately be slain by Túrin Turambar, the Man he cursed. By finally defeating Morgoth, Túrin will avenge not only himself, but all members of the race of Men.
Gandalf was one of the five Istari sent to Middle-earth by the Valar in the Third Age. In Valinor he was known as Olórin. Gandalf was instrumental in bringing about the demise of Sauron in T.A. 3019, chiefly by encouraging others and dispensing his wisdom at pivotal times.
'The Fellowship of the Ring' (2001)
If Gandalf had stayed dead after his sacrifice in The Fellowship of the Ring, then his demise would be the saddest in the trilogy, but since he came back, the saddest single death scene of all three movies goes to Boromir's.
It's possible that Gollum's prolonged search for the ring allowed it to maintain a significant power over him, suspending his aging process. In contrast, Bilbo's exposure to the ring's influence waned after he willingly (mostly) relinquished it, allowing his aging to resume more noticeably.
Sauron gave Nine of the Rings of Power to leaders of Men, who became "mighty in their day, kings, sorcerers, and warriors of old". They gained unending lifespans, and the ability to see things in worlds invisible to mortal Men.
Gandalf's spirit is estimated to be about 24,000 years old (by his own admission) and Sauron is likely the same age. Galadriel is at most 8,000 years of age. Galadriel was an elf, born in Arda.
while Sauron was more powerful than Gandalf in a direct comparison, their roles and methods were fundamentally different. Gandalf's strength was in enabling others to resist evil, while Sauron sought to dominate and enslave.
Sauron revived Isildur with one of the nine rings, and then tortured him until his spirit was broken and he became a Nazgûl. The specific power of his ring allowed him to raise the dead and have them fight by his side as mindless minions.
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.
His two most salient powers were his knowledge and his voice. Saruman was, in a very real way, the junior brother of Sauron both having been Maia of Aulë, Valar of Smithcraft, in the very beginnings of time.
It's not the years; it's the mileage. Gandalf isn't a Maia in the same way Sauron is. He was sent to middle earth as an old man, so his body is much more real than Sauron's “raiment”. He can't use his power to the same extent, he can't change his forms at will.
The Ent who figures most prominently in the book is Treebeard, who is called the oldest creature in Middle-earth.
Sauron needed Gandalf out of the picture permanently, as he was the only enemy with the knowledge, leadership and determination to thwart him. His biggest mistake was ego. He succeeded by trickery, by his ability to deceive others. He conquered so much land that his ability to control became out of reach .
But at the Council of Elrond, Gandalf very specifically says he fought all nine. He drew four of them off when he fled northward at dawn; "This helped, a little, for there were only five, not nine, when your camp was attacked."
Tolkien's description of Gollum conforms to a Catholic – and Thomistic – account of envy, which is a “sadness of the soul”; and it is Gollum's unbearable sadness and his unquenchable desire for the one Ring that marks his character.
Ryan Wikstrom - Sauron is a 'fallen angel' - the Maiar all have personalities of their own and can be corrupted. The Istari, including Saruman, were indeed Maia—essentially spiritual beings sent by the Valar (the gods of Middle-earth) to guide and aid the Free Peoples in resisting Sauron.