The Nightclaws, like the rest of the prisoners of the Labyrinth, were imprisoned there by Taurus ages ago. After Taurus vanished, and the prison fell into chaos, several of the monsters banded together for safety, and called themselves the Nightclaws. As supplies ran low they began cannibalizing the other prisoners they managed to capture, taking over a significant section of the Labyrinth and gaining a reputation among other inmates as a very dangerous gang.
Herne the Hunter
A monster covered in motley armor; his only distinguishing trait was his two-horned helmet, though one of the horns had broken off. He was the leader of the Nightclaws and the one to capture Casey.
A monster who may or may not have been part of the Nightclaws, but who delivered the Yellow Zeo Ranger to them when she entered the Labyrinth. He was an owlish, cowardly monster covered in ragged feathers and patchy armor.