NPCs: Local people and beings that can be interacted with...although this doesn't guarantee they aren't dangerous.
Monsters: These creatures include what seems to be hazardous wildlife, weaker spirits and dangerous beings, and other living hazards. They exist in numbers, and many of them can be overcome or avoided with proper precautions.
Ghosts: Highly individual, ghosts often have particular behavior patterns and habits, showing signs of the manner of their final death. Their apparent awareness and understanding of their surroundings is variable, as is how much a guest can communicate with them. They cannot be destroyed by any means available to the guests, and those who are exceptionally clever with use of surroundings powers will find any suppression or interference to be temporary.
Zoo: These unfortunate creatures inhabit the Zoo. A few of them will be on display on any given day, while at Night, they reside in cages in the Holding Room.