Since this is a question I’ve been asked a few times, and also something I’ve seen come up on other sites:

 
Contrary to what seems to be popular belief, animated objects don’t always require an NPC to run; whether they do depends on the type and complexity of the object and not just on whether or not it’s animated. Objects that move around the lot, like Rebecah’s farm animals, usually need an NPC to work, but simple animated objects like mine, that rotate/swing/rock in place, do not.

But if any object of mine did spawn an NPC (which I say again, they do NOT), I promise you it would say so very, very clearly in the upload post. I know there are creators out there who like to foist undisclosed features upon their downloaders, but I’m not that kind of creator.