Mobs:
Mobs, or mobile entities, are the living beings of dungeons. Some are docile, or won't attack a hunter. Others are reactive, meaning that they won't attack unless provoked. Most mobs found in Rare and Mythic dungeons are aggro, meaning they will attack hunters on sight.
Mobs have not yet been studied so they do not yet have a ranking system. Though sentient mobs, called boss mobs, can have their own skills. Mobs at this level are equal to higher level hunters or above that.