Celebrimbor was one of the greatest of the Elven smiths, save only maybe for his grandpappy Fëanor (dick). But who was he, really?
It should probably go without saying, but I’ma have spoilers below. If spoilers for 60- and 40-something-year-old books are an issue for you, you have been warned.
Celebrimbor was born in Valinor to Fëanor’s favorite son Curufin (called Curufin the Crafty, sooooo) and Nerdanel (guess I just found my Elf name!), another Ñoldorean Elf. When Fëanor made his infamous oath, Curufin took all of his sons and left Aman. Celebrimbor traveled with his dad and his uncle Celegorm to Belariand in the first age and lived in Himlad until they were defeated by Morgoth and fled to Nargathrond, where Finrod welcomed them (surprisingly, since Finrod opposed the Oath of Fëanor – and as such was the first Elf to be reincarnated in Aman).
Daddy Curufin and Uncle Celegorm turned out to be dicks just like their dad, and when Finrod asked them to go with him to help Beren (yes, that Beren) steal a Silmaril from Morgoth they declined, and in fact they convinced most of Nargathrond not to help either. With Finrod gone, C&C basically took over Nargathrond, and also they kidnapped Lúthien (yes, that Lúthien) but she escaped with a little help from her friends and they freed Beren and the others who were captured by Morgoth. When Beren and company returned to Nargathrond, the people there realized that C&C were dicks and they were exiled from Nargathrond. Celebrimbor stayed in Nargathrond, fighting in the sacking of the city, then escaping and traveling to Gondolin. He survived the Fall of Gondolin and stayed in Middle-earth, moving to Eregion in the second age.
Celebrimbor became friends with the Dwarves of Khazad-dûm, especially the Dwarf Narvi. The two were the greatest craftsmen of the second age and they collaborated to craft the Doors of Durin. When Galadriel and Celeborn left the capital city of Ost-in-Edhil for their new realm of Lothlórien, Celebrimbor became the leader of Eregion and the Gwaith-i-Mírdain (“jewel-smiths” or “Elven-smiths”) flourished.
“The Doors of Durin” by Anke Eißmann
Then the Elf Annatar (“Lord of Gifts”) came to Eregion. He claimed to be an emissary of the Valar Aulë and befriended Celebrimbor and the Ñoldor in Eregion. Annatar taught the Gwaith-i-Mírdain the art of ring-making, and they started forging rings of power.
Celebrimbor didn’t entirely trust Annatar, and it turns out that he had good reason not to. Annatar was actually SECRET SAURON disguised in a fair form. While the Gwaith-i-Mírdain crafted the 9 rings of Men and the 7 rings of the Dwarves with Annatar’s help, Celebrimbor forged three Elven rings after Annatar left Eregion. Celebrimbor unfortunately didn’t know that the craft Annatar taught them incorporated a binding magic; still, these three rings were uncorrupted by Sauron.
Sauron left Eregion and, in Mordor in the fires of the Cracks of Doom, forged the One Ring to rule all of the other rings the Gwaith-i-Mírdain had crafted. As soon as Sauron put the One Ring on, the jig was up and the Elves knew what had happened. Knowing his intentions with the rings, they kept the other rings from Sauron. Celebrimbor sent the three greatest rings away for safe keeping. He also sent the most powerful of the Dwarf rings to Durin III in Khazad-dûm.
Sauron was pissed about this and attacked Eregion. Celebrimbor was captured and tortured. He gave up the locations of the lesser rings, but wouldn’t tell Sauron where the Elven rings were, and he was killed. His tortured body was hung from a pole and paraded through the Grey Havens when Sauron attacked. a tragic end for the last of Fëanor’s line.