Fëanor's testimony revealed the malice of Melkor and his lies, and Tulkas immediately left the Ring to apprehend him again. Despite Melkor having been the true root of the Ñoldor's unrest, Fëanor's crime had been of his own making, and for this the Valar exiled him for a time to Formenos.
Yet when Morgoth, a big bad god, stole from the Elves and killed one of their leaders, several of them decided it was time to exile themselves from Valinor and wage war against him. After he was defeated, many Elves went back to the blessed lands, but some, including Galadriel, chose to stay.
Galadriel is supposed to be banned from return because she associate with the kin-slaying in Alqualondë or at least continued on from Aman and then was banned from return.
It was when Feanor and his sons rebelled against the Valar and the other Elvish kindreds, swearing an oath to reclaim Feanor's Silmarils, which had been stolen by the Dark Lord Morgoth.
Answer: Fëanor, easily. Look into both the characters and you'll see how unfair this is. Fëanor is theoretically the most powerful non-god/angelic character in Tolkien's entire legendarium and is the most powerful Elf upon Middle-earth. He's conceived as the mightiest of the Children of Ilúvatar.
He was one of the First-born Elves, and a proud and vengeful person whose fanaticism drove him to commit genocide against the Teleri. Fëanor was tall and dark-haired, typical of the Nõldor. He was charismatic but cruel.
Put simply, the Elves can't return to Valinor in The Rings of Power because their work in Middle-earth is unfinished. There is far more context to the situation in Tolkien's writing, but The Rings of Power skipped The Silmarillion's complexities regarding Elves and the War of Wrath.
All those Elves who never reached Valinor are "Dark Elves." In the First Age, the Sindar viewed the term "Moriquendi" as offensive, so the Noldorin Exiles gave the name Úmanyar ("Those not of Aman") to those who started the journey but did not finish it.
In mid-1967, Tolkien wrote long drafts of a letter, in which he first mentioned the idea of Galadriel not being allowed to return after the First Age as a punishment for being one of the leaders of the Noldor rebellion.
Yet no mortal can survive forever. And after their marriage, both Aragorn and Arwen are mortal. Arwen, therefore, could not set foot in the Undying Lands without special permission. And she wouldn't be likely to go after it in the end.
In the Fellowship of the Ring Book 2 Chapter 2 "The Council of Elrond", the potential for sending the ring over the Sea to Valinor is discussed. In it, Elrond notes: 'And they who dwell beyond the Sea would not receive it: for good or ill it belongs to Middle-earth; it is for us who still dwell here to deal with it.
The ship passed west upon the sea, and then took the hidden straight path to Valinor. Gandalf became Olórin once more. There, presumably, he dwells still in the gardens of Irmo.
Feanor was so inspired by Galadriel's grace and beauty, that he wished to use strands of her hair in the making of his three Silmarils, the most precious gems ever created in Middle Earth.
He was also the creator of the Palantíri. Fëanor was made the mightiest in all parts of body and mind; countenance, understanding, skill, and subtlety, of all the Children of Ilúvatar.
Celebrimbor was the son of Curufin, fifth son of Fëanor and Nerdanel, and Fëanor's only known grandchild. Fëanor was the most skilful craftsman of the First Age, forging the three Silmarils to capture some of the light of the Two Trees of Valinor. It is not stated where or when Celebrimbor was born.
Although in the latest version of the story, Galadriel's story changed significantly, far from joining Fëanor's rebellion, she opposed him in nearly everything. And that she wished to leave Valinor and go to the vast world of Middle-earth, to give free rein there to her talents.
They may be restored by the Will of the Valar, and then go to live with the Valar in Valinor, like an Earthly Paradise, though just being in the place does not confer immortality, as Men supposed.
By special permission of the Valar, the Hobbits Frodo Baggins, Bilbo Baggins, and Samwise Gamgee were also permitted to go to Valinor, as they had once borne the One Ring of Sauron. Later, after the death of Aragorn, Legolas the Elf would sail to Valinor and bring with him Gimli the Dwarf.
At that time, Círdan would abandon the Grey Havens and finally travel the Straight Road himself. On some unknown date, he sailed west aboard the Last Ship with his kinsman Celeborn, but when he did so, he took with him the last living memory of the Elder Days in Middle-earth.
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 this he (Tolkien) emphasized the commanding stature of Galadriel already in Valinor, the equal if unlike endowments of Fëanor; and it is said here that so far from joining in Fëanor's revolt she was in every way opposed to him."
Why did Feanor betray Fingolfin? Fëanor betrayed Fingolfin because even in paradise there was familial dysfunction. Elves are supposed to wed for life to one and only one mate. Finwë did the unthinkable, when he remarried after Fëanor's mother gave up on life.
