Exorcisms Outside Hollywood, Legit or Signs of Mental Illness?

Hollywood loves a good exorcism movie, but real people all across the world sometimes claim they are possessed by demons ... and there's real questions surrounding the authenticity of exorcisms.

TMZ Studios has a new series, "Strange & Suspicious," now airing on a dozen FOX stations, where we explore strange, unexplained and downright weird stories, and now we're looking into the validity of exorcisms.

Take Anneliese Michel in Germany for example ... she was allegedly possessed by a demon, who claimed they had a right to use her body until she "croaked."

While lots of exorcisms go down in private -- far away from the big screen and Hollywood scripts -- there are some that happen in church, often on camera.

Some of these more public exorcisms do seem a little performative ... which raises the question, are these folks really possessed or just suffering from mental illness?!?

There are other possible explanations too, some based on science or medicine ... but Anneliese feels more legit than others, and they're all pretty scary.

So, what's the deal here???