After King Aragorn (Elessar) died in the Fourth Age (F.A. 120), Legolas, feeling the call of the West and the loss of his mortal friends, built a ship in Ithilien and sailed across the sea to the Undying Lands, taking his dear friend Gimli the Dwarf with him—the only Dwarf known to have journeyed there. This marked the end of the Fellowship in Middle-earth, as Legolas fulfilled his longing to depart after Aragorn's passing, a bittersweet end to his long life in Middle-earth where he had helped restore the woods.
Eventually Legolas brought south many Silvan Elves, and they dwelt in Ithilien, and it became once again the "fairest country in all the westlands." They stayed in Ithilien for "a hundred years of Men." After Aragorn dies, Legolas built a small ship and sailed West, reportedly taking Gimli with him.
It was unknown if Thranduil had a change of heart, and stayed to aid the Dwarves. However, after the battle ended and regretting his mistakes, he goes to Ravenhill alone to find Legolas and Tauriel. He runs into Legolas, who confesses that he could not go back with him.
Frodo sails to the Undying Lands because the Ring's wounds--physical, psychological, and spiritual--left him unable to find full healing in Middle-earth. The voyage is a merciful, honored cure offered by the Valar and Elves, fitting both the character's sacrifices and the mythic structure of Tolkien's world.
She was mortal and had given up her place. Once Elrond set sail without her on board, her fate was sealed. Also, even if it had worked, that would've separated her soul from Aragorn's in the afterlife. So, for all of those reasons, going West was out.
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.
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.
Tolkien's Legolas is extremely introverted. He just doesn't have much to say directly to anyone, perhaps because he's thousands of years old. His odd relationship with Gimli draws him out in a way the hobbits never do, and that's mostly after Frodo and Sam leave the Fellowship.
The movie the Battle of Five Armies expanded on Tolkien's canon by saying that the white gems Thranduil wanted back from the dwarves were originally intended for her, but that she was captured and taken and tortured to death by Gundabad orcs before the order was completed.
He attacks the Orcs in rage, and is later confronted by Bolg. He saves Tauriel from being attacked by Bolg, but is mortally wounded during the fight. Kíli dies with Tauriel by his side. Bolg is eventually killed by Legolas while Azog is killed by Thorin himself avenging the brothers.
During their trip down the river, Legolas's far sight alerts him to the presence of the Uruk-hai scouts bearing down on them. At Parth Galen, Legolas urges Aragorn to lead them away immediately, as he can sense the Uruk-hai approaching.
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.
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.
After the battle and Thorin's death, Thranduil took Orcrist, which was previously confiscated in Mirkwood, and laid it upon Thorin's tomb. The treasure was divided among Elves and Men, and Thranduil received the emeralds of Girion.
But that's actually the answer: Eru Said So . The Undying Lands are a place for immortal beings (Eldar), and mortals are forbidden from entering.
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.
Instead, we have to consider that Sauron, the original owner, is not human, but has a quasi-divine status. Therefore ownership of the Ring is subject to Divine Law. With this precedent in mind, many of the ambiguities clear up nicely. After numerous transfers by violence and trickery, Frodo is the true owner.
In Valinor, Gandalf, a Maia, was named Olórin, one of the people of the Vala Manwë, and the wisest of the Maiar. He was closely associated with two other Valar: Irmo, in whose gardens he lived, and Nienna, the patron of mercy, who gave him tutelage.
The Ent who figures most prominently in the book is Treebeard, who is called the oldest creature in Middle-earth.
Power was never going to succeed in defeating evil. Gandalf was at exactly 12.35% of his full power as Gandalf the Grey, this went up of 18.237% as Gandalf the White. The Maia varied greatly, as did the Valar. Even at his fullest, Olorin/Gandalf was not the equal of Mairon/Sauron, not even close.
The Ring's effects
Inversely, the hobbits' good-naturedness and lack of ambition makes them less susceptible to the Ring's promises of power, as in Frodo and Samwise Gamgee, who are able to handle the Ring for extended periods of time.
If by my life or death I can protect you, I will. What does your heart tell you? But I am the real Strider, fortunately. I am Aragorn son of Arathorn; and if by life or death I can save you, I will.
Seven times Fingolfin wounded Morgoth and seven times Morgoth cried in pain, and seven times the host of Morgoth wailed in anguish, but he could not be slain for he was one of the Valar.