The Nightmare, the storm king and grogar.

My OC The Nightmare is the "father" of the real Grogar and the Storm King. In my fan stuff I have that the real Grogar is still alive, thats also why his Bell still works. He lives in the Shadow World. It is a mirror world to the World of Light which is Equestria and the lands beyond its borders.

The Windigos as they are are due to The Nightmare. They were once guardian spirits who tried to take down The Nightmare many eons ago. They failed to defeat him. He used his dark powers to corrupt the once noble creatures into what they are now.

The Nightmare corrupted Stygian like he had done with Luna.