The Mu Ganaelyn is a setting in the Metal Shadow universe. It is a mountain range in the Fifth Sky on which Castle Glas stands.

The Red Threat fought the Elemancing Guild here in what seemed to be the first public display of elemancy the people of the Fifth had ever seen. During the battle it was said that "mountains were leveled", and since the Mu Ganaelyn is the only mountain range in range of the battle, it must have been this mountain which was destroyed.