Grues are 7' tall, semi-bipedal creatures who prowl subterranean caverns and long-forgotten ruins. Cunning creatures, their most common tactic is to lie in wait for their prey to come near, and then snatch them. In fact, most of their lives are spent in total darkness, and they shun most light sources. Even the light of a torch is too bright for them. If forced to fight near any light source, a grue's morale immediately falls to 4.

Few people have seen a grue and lived to tell the tale. Most survivors agree that their skins tend to be scaly, and a slate grey in colour. Their heads are dominated by a large set of powerful, tooth-filled jaws, and their paws end in long, wicked claws. Other subterranean creatures shun grue caverns, and in fact some creatures have been known to draw their enemies towards known grue lairs, in the hopes that these hideous creatures will finish them off.

Grues possess very strong infravision, being able to see up to 120' in the dark, as well as well-developed senses of smell and hearing. Their lairs are littered with crushed bones and fragments of armour - the remnants of previous meals. Though they carry no treasure, their lairs do contain the valuables of past victims.