Celegorm's hound of Valinor.
Húan was given to Celegorm by Oromë in Valinor, and it is told that this was because Celegorm loved to follow Oromë hunting in the forest. Húan followed Celegorm into exile. Húan's gleaming eyes would pierce shadows and mist and his nose could follow a scent that was even a month old and Morgoth's wolves were deathly afraid of him. It is told of Húan that he would meet death but not until he encountered the mightiest wolf that would ever walk the World. Húan could understand speech, but he chose to speak only thrice before his death.
F.A.465. Húan found Luthien sleeping while he was hunting wolves with Celegorm and Curufin near the eaves of Doriath and he brought her to Celegorm. But when Luthien was imprisoned in Nargothrond he became friends with her. Here he spoke for the first time, and helped her escape. Húan followed Luthien to Tol-en-Gaurhoth where he overthrew the werewolves, Draugluin, and Wolf-Sauron, and with Luthien rescued Beren.
The same year Húan finally forsook the service of Celegorm when Celegorm and Curufin tried to kill Beren and Luthien near the eaves of Doriath. Beren departed from there continuing on his quest for a Silmaril, leaving Luthien in the care of Húan but Luthien persuaded Húan to follow Beren and bring her to him.
F.A.466. On the way, Húan pondered what counsel he could give to help them with the impending peril. As they again reached Tol-en-Gaurhoth he turned aside and took the pelt of Draugluin and the cloak of Thuringwethil and clad in these Húan and Luthien reaches Beren at the borders of Anfauglith. Then he spoke the second time to Beren and Luthien, advising them to wear those garments for disguise.
Húan met Beren and Luthien again at the borders of Doriath after their flight from Angband and he helped Luthien tend Beren. After the return to Menegroth tidings came of Carcharoth who burst into Doriath and that a hunting party was gathered to destroy the perilous wolf. Thingol, Mablung, Beleg, Beren and Húan rode forth in the morning. They crossed the river and came upon Carcharoth in a valley at the falls of Esgalduin. Húan chased Carcharoth out of hiding and Carcharoth leaped upon Thingol. Beren strode before Carcharoth with a spear but Carcharoth avoided it. Carcharoth fell, with Beren biting on his breast. At that moment, Húan attacked Carcharoth from behind and there they fought to the death. Húan slew Carcharoth but there in the woven woods of Doriath his own doom was fulfilled and he was mortally wounded. Laying beside Beren, who was also mortally wounded, Húan spoke for the third and last time and bade Beren farewell.
Related links.: Encyc.: Húan.