Wargs were bred from cursed Wolves. Unusually large and fierce, they were also more intelligent than their canine ancestors. They served as mounts for Orcs and as guards and scouts for Morgoth.
Wargs appeared in two different breeds, common wargs and true wargs.
- Common Wargs were just an extremely large breed of war-wolves, bred by Morgoth from ordinary wolves in the first age. The Mountain Wargs or Grey Wargs were of this kind, the Frost-Wargs of the Forodwaith were bred by the Ice-Orcs by interbreeding Wargs with White Wolves. The Isenwargs or War-Wargs were a breed created by Saruman of common Wargs and wild eastern Beasts.
- True Wargs or Ghost-Wolves (Also known as Black Wargs, Shadow-Wargs, Dire-Wargs, Fell Wargs, Shadowmaws, Warg-Wights or Deg-lic) were lesser Were-Wolves, undead spirits incorporating the bodies of degenerated and magically altered great wolves. Being artificially long-lived, undead, the spirit that inhabited a true Warg's form dissipated when the body was slain. In turn, the body disappeared.