A Wolf
A Wolf were four-legged carnivorous wild dogs which lived in Middle-earth.
Species
There were many types of wolves in Middle-earth like, and usually they lived in a pack in the wild and were one of the many different beasts in the world of Arda, these types included groups like White Wolves. However, wolves were sometimes dark beasts often used by agents of evil like Wargs and Werewolves. Sauron, during his service to Morgoth, took the shape of a wolf at least once.
Society
Wolves were capable of governing themselves without a dark lord. They lived in packs ruled by an alpha male and female and used teamwork to take down anything they could catch and kill, including hobbits. Wolves, like many other animals in Arda (fellbeasts, 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. The Wargs may have allied with Orcs at times simply for the benefits of domestication, but this was never canon. The Werewolves from the First Age were actually bred from normal wolves possessed by evil spirits sent by Morgoth.
History
It is unknown if wolves were created just as the other middle-earth beasts were created, or if they were created by Morgoth. Durring the first age, the only known time they fought for Morgoth was Durring the War of Wrath, most of the wolves were slain, but a few survived and fled to safety. During the third age the wolves who lived in Angmar pledged loyalty to The Witch King. It is unknown if they joined by their own will or if they were forced to join the armies of Angmar 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 survived to this day.
Portrayal in adaptations
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 "Hound 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.
In other media
In The Lord of the Rings: The Battle for Middle-earth II: The Rise of the Witch-king there are also Dire wolves in the Angmar faction.
The Shade of the Wolf in BFME II, ROTWK
