Fell Wargs

The Fell Wargs are a vile race of Wolves.While the lesser Wargs are just greater Wolves the Fell Wargs are intelligent beasts possessed by evil Spirits, therefore Fell Wargs are also considered (lesser) Werewolves ("Gaurwaith").

They are known under various designations True Wargs, Ghost-Wolves, Shadow Wargs, Dire-Wargs, Shadowmaws, Warg-Wights and Deg-lic.The common Wargs or Mountain Wargs and their northern Frost Warg Cousins are just their lesser descendants and the common steed bred by the Orcs in their caves.The Fell Wargs are however a race that lives under it's own rule and only join their Orc-comrades on and off as equal allies.The Warg's Ruler is the semi-legendary Warg-King.

Books
The Warg-pack the Fellowship of the Ring had to fight in Eregion were greater Wargs.Their bodies diminished after they had been slain and Gandalf adressed them as Gaurwaith and stated that these were not normal Wolves.

Movie Trilogy
In the Hobbit Trilogy the Fell Wargs are the companions of Azog and his Hunter-Orcs.