In J. R. R. Tolkien's mythology of Middle-earth, Carcharoth (pronounced [ˈkarxarɔθ]), Sindarin for "The Red Maw", was the greatest wolf that had ever lived. He was also called Anfauglir (Jaws of Thirst; IPA: [anˈfaʊɡlir]). He was bred with the specific goal of killing Huan, the hound of Valinor, a goal in which he succeeded (Morgoth, as well as his most powerful servant Sauron, was aware of the prophecies regarding Huan's death and set out to make the prophecy come true).
Born of the foul breed of the Wolves of Angband and fed by Morgoth's own hand with Elvish and man-flesh in which Morgoth deliberately infused his own powers, Carcharoth tirelessly guarded Morgoth's Dark Throne in Angband.
He became involved with the Quest for the Silmaril when Beren and Lúthien had to pass him on their way into Angband. Lúthien enchanted him with her magic, but on their way out Carcharoth attacked before Lúthien could enthral him again. Beren held out the captured Silmaril in an attempt to stay the beast, but Carcharoth bit off Beren's hand and swallowed it together with the Silmaril.
The Silmaril burned away Carcharoth's insides, and he became crazed with pain. A terror to Elves, Men and Orcs alike, he passed south through Beleriand until he arrived in Doriath. There Beren Erchamion, Elu Thingol, Beleg Cúthalion and Mablung joined with Huan the Hound to hunt the Wolf.
Carcharoth was killed by Huan, but Huan died soon afterwards from his wounds. When Mablung cut open the belly of Carcharoth, he found there the Silmaril with Beren's hand still around it, but when he touched the flesh it was swept away by a wind. Beren then died of his wound, but returned later after Lúthien's pleas to Mandos.
Tom Shippey, in The Road to Middle-earth (pp. 193–194) says that the hunting of the great wolf recalls the chase of the boar Twrch Trwyth in the Welsh Mabinogion, while the motif of 'the hand in the wolf's mouth' is one of the most famous parts of the Prose Edda, told of Fenris Wolf and the god Týr; while Huan recalls several faithful hounds of legend, Garm, Gelert, Cafall. Jane Chance, in Tolkien the Medievalist (p. 265, 2003 edition) in addition to mentioning the parallels with the boar hunt in the Mabinogion, additionally compares the hunt for Carcharoth to the hunt for the Calydonian Boar, a tale from Greek mythology.
In Ancient Greek καρχαρο (karcharo) means "jagged" or "sharp".