In J. R. R. Tolkien's fantasy book The Lord of the Rings, Celeborn (pronounced with a hard c as in cat) is the Elven husband of Galadriel; Lord of the Galadhrim; and co-ruler along with Galadriel of Lothlórien. He is the father of Celebrían, the wife of Elrond, and thus the grandfather of Arwen Evenstar and her older brothers Elladan and Elrohir. He is also believed to be a kinsman of the First Age Elven King Thingol. Celeborn means "(tall) silver tree" in Sindarin.
He is also referred to as Lord of Lothlórien, or Lord of the Wood interchangeably. Within Lothlórien itself he is called simply Lord Celeborn or The Lord (more often with Galadriel as The Lord and Lady).
Celeborn is also the name of the White Tree that flourished in Tol Eressëa. It was a seeding of the tree Galathilion, which in turn was made by Yavanna in the image of Telperion, the eldest of the Two Trees of Valinor. Celeborn was an ancestor to the White Trees of Númenor and of Gondor.
Most existing writings portray Celeborn as a Sindarin Elf from Doriath, the kingdom of Thingol. He is described as a "kinsman" of Thingol. That Celeborn and Thingol are remotely related is further alluded to by the fact they both have silver hair, a colour which is never mentioned outside of the royal house of the Sindar. This origin was adopted by Christopher Tolkien and Guy Kay for The Silmarillion when it was decided to publish this book after Tolkien's death, and a new paragraph about Celeborn's marriage to Galadriel was inserted. Exactly how Celeborn could have been a kinsman of Thingol was not mentioned. Celeborn's silver hair, considered a rare colour among the Elves, is particularly noted as associated with the House of Elwë and Olwë. Míriel Serindë, mother of Fëanor, also has silver hair, as did Eärwen, daughter of Olwë, mother of Galadriel. Míriel, by this measure, is possibly related to the Sindar, as she may be, like Eärwen, only Noldor by marriage, as far as is known.
According to one speculative text written by Tolkien, published as part of the Unfinished Tales, Celeborn is the grandson of Thingol's younger brother Elmo (who never appears elsewhere). Elmo is also linked to Círdan, making Círdan another member of the Sindarin royal house.
This simple origin was later changed: in Tolkien's last writings Celeborn is a Telerin Elf from Valinor, then named Teleporno in Telerin Quenya. (This brings him closer to being a peer and equal to Galadriel and makes their partnership seem more balanced.) He meets Galadriel when she is living in the Telerin city Alqualondë, before the rebellion of the Noldor. They decide to travel together to Middle-earth, without asking permission from the Valar to do so. While not involved with the rebellion of the Noldor, because they leave at the same time and without permission (which would certainly not have been granted at that time), Celeborn and Galadriel are caught under the same Ban that prevents them from returning. The name Teleporno was then "Sindarized" as Celeborn: Telerin telep ("silver") (Noldorin Quenya tyelep) was translated to Sindarin keleb (or celeb). In order to be counted as a kinsman of the Sindarin king Thingol, Celeborn must have been part of the family of the Telerin king Olwë, likely one of his sons or grandsons.
This altered origin was not adopted into the published Silmarillion, primarily because it would have necessitated a major rewrite of the earlier parts to account for a separate departure of Galadriel. A further problem was that this descent would have made Celeborn Galadriel's first or second cousin (assuming that he was still to be considered closely related to Thingol), and Elves never married close kin.
Unfortunately, Tolkien's "final word" on Celeborn's origin is unknown, as he never returned to the question. While it is likely the Aman origin of Teleporno was the final intent, it is equally likely Celeborn would have been portrayed in the eventual "author's Silmarillion" as related more distantly to Thingol—the relationship could have been through other family members not mentioned. (See Daughters of Finwë for an example of significant family members not named in The Silmarillion.)
Celeborn's further history is as unclear as his past: at one point during the Second Age, Celeborn apparently ruled over Elves in Lindon, but it is not certain if he fell under the overlordship of Gil-galad, or ruled (together with Galadriel?) as an independent lord. Celeborn and Galadriel later rule over the Elves of Eregion (at least in some accounts), before settling in Lothlórien.
Celeborn relocated across the Anduin with many of the elves of Lothlórien at the end of the Third Age to found a new, larger realm, 'East Lórien', but left there for Rivendell to join his grandsons Elladan and Elrohir when Galadriel left Middle-earth shortly after this.
Celeborn is also the name of the White Tree that grows in Tol Eressëa. It is a seeding of the tree Galathilion, which in turn was made in image of Telperion, the eldest of the Two Trees of Valinor. The tree Celeborn is an ancestor to the White Trees of Númenor and of Gondor.
Celeborn is also referred to by numerous name, including "Teleporno" - the High-elven version of Celeborn, "Prince of Doriath", "Celeborn the Wise" a name given him by Galadriel as she said he was the wisest of the Elves in Middle-earth and "Lord of Lothlórien" or "Lord of the Wood".