Location from My Little Pony: Friendship Is Magic by Hasbro / Lauren Faust
Equestria's supernatural prison — a hellish underworld guarded by Cerberus, holding the worst monsters and villains.
Tartarus is where Equestria puts the things it can't destroy. The gates are guarded by Cerberus, who occasionally wanders away from his post — which is how Tirek escaped. Inside, the most dangerous creatures in Equestrian history are held in magical containment: chimeras, ancient monsters, and anyone too powerful to be reformed or reasoned with. It's not a place of punishment so much as a place of containment. The moral complexity of Equestria's justice system lives here — in a world built on friendship, what do you do with beings who refuse it?
A dark, cavernous realm beneath Equestria, accessed through massive gates guarded by Cerberus — a three-headed dog of enormous size. The interior is a vast underground network of cages, cells, and containment areas, dimly lit by guttering magical flames. The air is stale and ancient.
Also known as: Tartarus