In the fiction of J. R. R. Tolkien, Galadriel, the Lady of the Woods, was an Elf-queen of Middle-earth, ruler of the land of Lothlórien along with her husband Celeborn.
She was originally named Artanis ("noble woman") and Nerwen ("man-maiden", referring of her height and strength). Galadriel is the Sindarinized version of Telerin Quenya Alatáriel, the name given her by her lover Celeborn, meaning "maiden crowned with a garland of bright radiance", which referred to her hair. The Elves of Tirion said it captured the radiance of the Two Trees Laurelin and Telperion themselves. It was greatly admired by Fëanor and may have inspired him to create the Silmarils.
Name Galadhriel was used outside Lórien by the people who did not know the ancient days and Galadriel's history, confusing with the Elvish word galadh ("tree") and the name of the Galadhrim, the people of Lórien.
Galadriel was the only daughter and youngest child of Finarfin, prince of the Ñoldor and of Eärwen, who was remotely related to Lúthien. Her elder brothers were Finrod Felagund, Angrod and Aegnor. She was born in Valinor during the Years of the Trees.
Much of Galadriel's story is confusing, and there are several distinct tales told about her, collected in the Unfinished Tales. According to the older account, used in the published Silmarillion, Galadriel is an eager participant and leader in the rebellion of the Ñoldor and their flight from Valinor, however completely separate from Fëanor and his kin. Once in Beleriand, she lived nominally with one of her brothers, but spent much time at the court of Thingol and Melian in Menegroth, where she was welcomed because of her family relationship to Thingol's brother Olwë (Galadriel's maternal grandfather). She met Celeborn, a kinsman of Thingol, in Doriath.
According to later accounts, Galadriel was living with her mother's kindred in the Telerin port of Alqualondë when she met Teleporno (later known as Celeborn), who would be her husband and co-ruler. During the great perturbations at the end of that period, she and Teleporno sailed from Valinor and came to Beleriand separately from most of the Ñoldor. Galadriel was not directly involved in the revolt of the Ñoldorin princes and even unaware of the Kinslaying at Alqualondë, but she fell under the Ban of the Valar because she left without permission (at a time when it would certainly not have been granted). Once in Beleriand she and Celeborn were welcomed by Thingol and lived in Doriath. Celeborn, by this account, must have been a son or grandson of Olwë, and would have been especially welcomed for that reason. Once the Ñoldor arrived Galadriel reestablished contact with her brothers, although she was an enemy of the sons of Fëanor: in these later accounts Galadriel and Fëanor are described as great enemies even in Aman.
In both accounts Celeborn played no important rôle in the Battles of Beleriand. Both Celeborn and Galadriel survived the War of Wrath, but refused the pardon offered by the Valar. Galadriel refused out of pride and therefore remained under the Ban. Celeborn and Galadriel travelled first to Lindon, where they ruled over a group of Elves, probably as a fiefdom under Gil-galad. Later they moved eastward, and established (or were welcomed in) the realm of Eregion or Hollin. At this time they made contact with a Nandorin settlement in the valley of the Anduin, the later Lothlórien. Later they removed from Eregion by way of the mines of Khazad-dûm, and became lords of Lothlórien. Celebrimbor now ruled over Eregion. In Lórien Galadriel and Celeborn had a daugher, Celebrían, who later married Elrond Half-elven of Rivendell.
During the Second Age, when the Rings of Power were forged, Galadriel was mistrusting of Annatar, the loremaster who guided Celebrimbor and the other Ñoldor of Eregion. It later turned out that this mistrust was justified, as he was finally revealed to be Sauron. When Eregion was attacked, Galadriel was entrusted with one of the Three Rings of the Elves. Her Ring was Nenya, the Ring of Water. Conscious of Sauron's power, and wishing to thwart it, she did not use the Ring as long as the One Ring was in Sauron's hands. However, during the Third Age, when the One Ring was lost, she put it to use. Its power might have been related to the Mirror of Galadriel, a large bowl of water in which visions of the past, present, and future could be seen.
In The Lord of the Rings, Galadriel hosted the Fellowship of the Ring after their escape from Moria. When she met them in her tree dwelling at Caras Galadhon, she gave each member of the fellowship a searching look, testing their resolve (Boromir regarded this test as a temptation). She, in turn, was tested when Frodo Baggins later offered to place the One Ring in her keeping. Knowing that its corrupting influence would make her "great and terrible", and recalling the ambitions that had once brought her to Middle-earth, she declared, "I pass the test" and refused the Ring, accepting her fate of diminishing (as the time of the dominion of Men had come) and returning at last to Valinor. When the Fellowship left, she gave each member a gift and an Elven cloak, and outfitted the party with boats and supplies.
She passed over the Great Sea in the early years of the Fourth Age (on the same ship as Elrond, Gandalf and the Ringbearers Bilbo and Frodo Baggins), leaving her husband Celeborn behind until he finally set sail as well. It is her refusal of the One Ring that lifts the Ban, and that is why she is finally allowed to return.
In Peter Jackson's movie trilogy beginning with The Lord of the Rings: The Fellowship of the Ring, Galadriel is played by Cate Blanchett. In the movie adaptation of The Fellowship of the Ring, Galadriel narrates the Prologue, explaining the creation of the Rings of Power and the War of the Last Alliance. Earlier plans considered were to have either Frodo or Gandalf narrate the Prologue, but this was dropped: Frodo wasn't alive until thousands of years after these events happened, and although Gandalf was alive, he was not present in Middle-earth at the time; the Wizards came some one thousand years after the Prologue ends. Thus Galadriel narrates the Prologue, because she had first-hand accounts of this history and actively participated in its events.
Later in the films, Galadriel frequently seems to be consulting telepathically with Elrond; there is some indication from the books that the two were able to communicate in some way, but the specific instances in the movies (particularly the discussion with Elrond in The Two Towers) have no direct counterparts in the books. She does at one point send messages to Aragorn and certain members of the Fellowship, which do not make it into the movie. Further, the notion that Galadriel would send her warriors to assist at Helm's Deep is practically unthinkable in the context of the books, where Lórien is itself under threat of attack at the time.