Caranthir, also known as Caranthir the Dark, was one of several sons of the Elf Feanor and like him was an uncommon case of a villainous Elf in Tolkein's Middle-Earth. Along with his siblings, he swore an oath to recover the stolen silmarils at any cost, and like his siblings engaged in mass kinslaying against his fellow Elves in the name of this oath. Of all of Feanor's sons, he was also the most ill-tempered and quick to anger.
Caranthir was born during the Noontide of Valinor. He came to Middle-Earth in the First Age and, along with his fellow siblings pursued their father's stolen Silmarils relentlessly, waging war with not only Morgoth's armies but their own kin as well. They also set up kingdoms for themselves in Middle-Earth, and Caranthir was no exception. But in his case, because it was near the Dwarven kingdoms of Nogrod and Belegost, he prospered and grew wealthy from dealings with the Dwarves.
Though willing to kinslay, Caranthir did also fight against Morgoth's armies, and rescued Edain lady Haleth and her people from Orcs at one point, also being impressed by the bravery the race of man demonstrated during the conflict.
In FA 506, his and his sibling's multiple acts of kinslaying finally caught up with them; Caranthir, along with his brothers Celegorm and Curufin, were killed trying to take the Silmarils from the Elven King Dior.
- One of the Elven villains in The Witcher: Wild Hunt, Caranthir, is named after him.