The Stinents, Klotkin Sisters, the two women, and Anna Clark (spoilers)
Malcolm Stinent said at the party for the cat that "they come back here a lot". So, were these people allowed of out hell anytime they wanted? How could they visit their old apartment all the time when they were dead and in hell. I could understand if they were ghosts, but these people were damned souls. Did Satan just choose random people who were condemned to burn in hell to be in his legion? Could they leave the apartment building if they wanted? Perhaps when the souls entered into our dimension through the portal that they forgot they were dead. However, you would think that after the birthday party and when Alison left Chazen's apartment, those people would be screaming knowing that they had to return to hell and were actually dead.
I understand that Chazen was Satan/the devil.
Also, we know that Anna Clark was executed for murder. However, we later find out that some of those people at the part were put to death for things like manslaughter. I didn't think that was punishable by death.