How many times have you seen it? Are you certain it isn't something else you are catching out of the corners of your eyes? Could it be a light coming from somewhere?
If it is indeed paranormal it can be a number of things.
It could be a passed individual appearing differently. Usually when I see apparitions they do not all appear the same to me. They have differing features and are sometimes seen as shadows against the wall. I remember seeing the shadow of a woman in a gown with hair up, this person not being present in the room, not anyone around me in a gown.
It could be another type of entity as well. Determining which has more, in my opinion, to do with how it behaves and less so with appearance. If it is paranormal in nature and not the lighting in your space.
I know for a fact it is not the lighting. It has a humanoid figure. I will watch it walk into the same room as me and it will freeze then disappear after a minute. It doesn't interact with anything as far as I know but I also have a cat so its hard to tell who's messing with things in my house.