The Warg (Mount) is a Ragnarok Online-exclusive combat mount that is only available to the Ranger job class. In addition to being a mount, the Warg can also be an offensive pet, much like the Hunter and Sniper-exclusive Falcons.
In Norse mythology, a vargr (often anglicised as warg or varg) is a wolf and in particular refers to the wolf Fenrir and his sons Sköll and Hati. Based on this, J. R. R. Tolkien in his fiction used the Old English form warg (other O.E. forms being wearg and wearh) to refer to a wolf-like creature of a particularly evil kind.