Here are all the nightmare pony OCs that I've made. For more information on nightmare ponies, see here.

King Cauchemar and Queen Phant

The Champions

Broken Mirror
Redsky Morning
Nycto
Rainy Parade
Arachno
Agora

Flashforce Focus
Sour Note
The Bloodspray Squadron
Glitz (technically not a pony, but he serves one)
Anopheli

You can use these ponies in your stories or roleplay as them, just make sure you ask and give me credit. I reserve the right to say no if I so choose.