Tulpa is a concept originally from Tibetan Buddhism and found in later traditions of mysticism and the paranormal of a materialized being or thought-form

The Theosophist Annie Besant, in the 1905 book Thought-Forms, divides them into three classes: forms in the shape of the person who creates them, forms that resemble objects or people and may become ensouled by nature spirits or by the dead, and forms that represent inherent qualities from the astral or mental planes, such as emotions.

The Slender Man has been described by some people as a tulpa-effect, and attributed to multiple people's thought processes.