Scientology calls them "BodyThetans".
You think I'm kidding?
Well then, allow me to prove it. Beyond any doubt. Click here to read three pages from these teachings. Scientology tried, and still tries, to get these pages removed from the Internet - by means of lawsuits.
Although lawsuits aren't funny, it sure is funny to see to what length Scientology goes to prove that these silly teachings really are from the "Source": L. Ron Hubbard®.
Or more precisely: about how to exorcise them...
And that's all dedicated Scientologists do - for the rest of their life...
They call this "The Bridge to Total Freedom".
The 1995 price-list of the courses that will ultimately learn you how to be a skilled BodyThetan exorcist can be found here.
A few documents however are still on-line, see below.
To make the reduction good, a bit, 250 up-to-date
The World Institute of Scientology Enterprises
On this page (in the Dutch section) there are hyperlinks to some other ("confidential") English Scientology documents.