Warbear Leather
Warbear Leather is not a normal leather that can be skinned from any creatures. The best place to skin Warbear Leather is by slaying Tainted Black Bear located just west of The Dark Portal in Blasted Lands. The Tainted Black Bear respawns reasonably fast so its a good place to farm.
See below for the map to farm Warbear Leather in WoW.