This is an article my friend wrote a while ago, trying to explain the various creatures, objects and places featured in Supernatural to non-watchers.
Creatures and beings
Spirits / Ghosts
• Ghosts of people who have died, are still here for: revenge, just an evil soul naturally, unfinished business
• Some spirits may only be seen by certain people – those with psychic abilities, those the spirits wish to harm or contact, or those in a certain state of mind.
• Ghosts are tied to one place and cannot leave it, usually where they died.
• Ectoplasm*
• Can make lights flicker on and off, move...
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