How to avoid an object to be reflected

I couldn’t find anything on the Internet: all articles and pages speak about how to obtain the reflection, but not how to avoid it.

I have a scene and a mirror in the scene that should reflect all objects BUT ONE (you can think of a vampire that is not reflected by the mirror). How can I accomplish this?


Use a separate render layer.
Or mirror the scene and get rid of the mirror itself. (this has actually been done in some Hollywood movies with a double for anyone facing the mirror)