Wraiths
From UnderlightWiki
Wraiths: various other prisoners who were corrupted by rage/lust/power/ego/etc in the Palisade. These became more well-known later, when the Wardens guarded the Palisade. They come in various forms and with various agendas. It is widely believed that if anyone is guilty of their accused crimes in the Palisade, they definitely are.