The Four Kings
The Four Kings were the rulers of the empire of Astora. They were relatively fair and just rulers at the start, but the first king of the four did not feel he had enough power, and began delving into the black arts of the Occult. There was a Fifth King, but he left when the others became sorcerers. Eventually, the kings went too far, attempting to summon an entity from Somewhere Else. It proved too difficult, and corrupted the kings as well as the rest of Astora. The Kings became spectral beings, with the only purpose of draining the life of any who dare venture into Astora in the hopes of regaining their humanity. The citizens of Astora became ghosts, stealing the souls of anything they could slay. Many of the ghosts are adventurers, killed by the ghosts, but unable to leave to a better place as they lost their souls. They have anger towards anyone who enters Astora, as they are jealous that they aren't trapped there. They try to slay them and take their souls, and therefore leave. The only thing left is the Sentinels, huge armored knights who seem indestructible, fighting and fighting the ghosts. They never sleep, or need to drink or eat. They never die. They will be there forever, until time itself fades away.