In parapsychology, ectoplasm is the name given to a hypothetical form of dense spiritual energy liberated by living things which is claimed to make possible the materialisation of ghosts.

In the early twentieth century, photographs claiming to show ectoplasm produced by physical mediums were occasionally published; these were largely shown to be fraudulent. Often the medium would have concealed cheesecloth or a similar substance about their person to produce at an appropriate moment.