What do you call a person who claims to be able to contact the dead?

People who claim to communicate with the deceased are known as mediums.

They also often claim to have contact with other guides or controls.

Physical mediums produce physical manifestations along with spirit voices in their seances. Mental mediums confine their communications to relaying information they receive from their communicators.

Mediumship is considered problematic by many people for various reasons. One is that it seems impossible to contact the deceased if in fact the mind is a by-product of a living brain. However, current theory strongly suggests that mind by in fact be separate from the living body. If this is true, then the practice of mediumship makes a bit more sense.

Parapsychology research extends to studies of mediumship. What has been shown conclusively is that anomalous information reception is indeed possible in gifted subjects. This does not mean they are necessarily communicating with the deceased, but it does demonstrate that knowing information one should not is in fact possible.

It is also important to know that many people claim mediumistic abilities. Given that only gifted subjects have been rigorously tested, it would be wise to regard untested claims of mediumship with some suspicion.