When discussing various forms of Inhuman Hauntings, it's important to understand that the terminology differs greatly from person to person...

Most people, as soon as they here "Inhuman" they immediately think;  Demon!

I think it would be rare to come across anyone with experience in this field who would dispute the existence of Poltergeists.  These are generally considered to be noisy spirits, however their origins and causes are contested.

Another contested type of haunting that is not a human spirit is often called a Portal.  These are considered mostly speculation even among those in a field where virtually everything we consider factual is considered speculation by others.

What might be the most widely known type of haunting, and definitely the one that first captured my imagination as a kid was an Inanimate Haunting.  Do you know anyone who hasn’t heard of the infamous Flying Dutchman (and I don’t mean opera fans)?  Inanimate hauntings are just what you’d think.  The appearance of an inanimate object, usually a ship or a train in my experience, which in reality is long gone.