The Wolves were four-legged carnivorous wild canines which lived in Middle-earth.
Dogs were domesticated from Gray Wolves by Men, and were their natural allies. Werewolves were bred from Gray Wolves inhabited by demons, and were minions of the Dark Powers in the first age. Wargs were a large, intelligent race of wolves who were the natural allies of the Orcs, and were most likely decendents of the Werewolves. The White Wolves were a mysterious race of unknown origin who inhabited the frozen Northern lands. For all intents and purposes, the White Wolves appeared to be neutral.
Wolves, like many other animals in Arda (crows, bats, burden beasts, mumakil , etc.) naturally have nothing to do with forces of darkness and it's strange that they served the Dark Powers at times, although it is known how they came into service. Carcharoth, Draugluin and the other evil wolves of the first age were just normal wolves possessed by evil spirits and the Wargs may have been descended from them.
It is unknown if wolves were created just as the other middle-earth beasts were created, or if they were created by Morgoth. During the first age, the only known time they fought for Morgoth was During the War of Wrath, in which most of the wolves were slain, but a few survived and fled to safety. During the third age the wolves that lived in Angmar pledged loyalty to The Witch King. It is unknown if they chose to join the armies of Angmar, or if they were forced to against their will. They fought in many battles against Arnor and presumably continued to thrive in Angmar after its final defeat. After Sauron's final defeat, wolves most likely continued to survive, and most likely survive to this day.
Portrayal in adaptationsEdit
The Fellowship of the Ring, in the book, was attacked by a pack of wild wolves the night after they came down from Caradhras. Gandalf, who addressed the first wolf to attack as "Hounds of Sauron" said after the fight was over, that the wolves weren't ordinary wolves because there were no bodies left nor any sign of the wolves at all. During the time of the War of the Ring, Saruman kept some wolves in Isengard. Also Gandalf sees Saruman's wolves while he is Saruman's prisoner at Orthanc.
In Peter Jackson's film trilogy, Wargs are present in The Two Towers. They attack the fleeing citizens of Edoras as they make for Helm's Deep, killing several soldiers of Rohan's small army before returning to Isengard. This attack only happens in the movie and is not used in the book.
According to prophecy, Huan would not die until he had encountered the greatest of all wolves, so Sauron contrived to take on that role and defeat the hound. He failed, as the greatest of all wolves was not Wolf-Sauron, but Carcharoth of Angband, and through Lúthien's magic and Huan's valour Sauron was defeated. Surrendering his tower on Tol-in-Gaurhoth, he fled in the form of a vampire into the woods of Dorthonoin, and was not seen again until after the War of Wrath. (J. R. R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Quenta Silmarillion: Of Beren and Lúthien")