In Spiritualism, paranormal literature and some religions, materialization is the creation or appearance of matter from unknown sources. The existence of materialization has not been confirmed by laboratory experiments. Numerous cases of fraudulent materialization demonstrations by mediums have been exposed.

In spiritualism, ectoplasm, also known as simply ecto, a substance or spiritual energy "exteriorized" by physical mediums. It was coined in 1894 by psychical researcher Charles Richet. Although the term is widespread in popular culture, there is no scientific evidence that ectoplasm exists and many purported examples were exposed as hoaxes fashioned from cheesecloth, gauze or other natural substances.