Spakes: Mythologically real creatures. They stalk you, kill you with knives, and feed off of your soul.
Innocents: Basically, virgins who are stalked and killed by Spakes.
Connectors: Innocents who were killed improperly by Spakes. Ghost-like entities that are neither living nor dead.
The Originals: The first five Spakes (later six, including Habakkuk) who were pulled into this reality from their own by certain Ancient Egyptian Scribes.