There have been theories put forward that cryptids are Tulpas. So what is a tulpa?
A tulpa is a thought form , a manifestation of mental energy, A being or object created out of thought that sometimes manifests in the “real world” so that others can see it, interact with it .Some people have found that Tulpas tend to reflect the worst of the person .The petty fears, desires and anger that we all bury inside ourselves can come out in the Tulpa.
What evidence is there for their existence?
When Alexandra David-Neel journeyed through Tibet, one of the many techniques she studied was that of tulpa creation. A tulpa, according Tibetan doctrines, is an entity created by an act of imagination. David-Neel decided to try to create one. Her tulpa began its existence as a plump, benign little monk. Then the apparition slipped from her conscious control. She discovered that the monk would appear from time to time when she had not willed it. The friendly little the figure was now taking on a distinctly sinister aspect. Eventually her companions, who were unaware of the mental disciplines she was practicing, began to ask about the "stranger" who had turned up in their camp-a clear indication that a creature had become real. David-Neel decided things had gone too far and applied different techniques to reabsorb the creature into her own mind. A sort of exorcism . The tulpa proved very unwilling to comply so that the process took several weeks and left its creator, David-Neel exhausted.
See : Body Mind & Spirit: A Dictionary of New Age Ideas, People, Places, and Terms [Paperback]Eileen Campbell (Author), J. H. Brennan (Author), Tuttle Pub; Rev Exp Su edition (Feb 1994)
So if anyone concentrated enough they could produce their own tulpa in theory. Usually though when people see cryptids they are not concentrating and quite often not expecting to see anything. Could the sub conscious mind produce the tulpa/cryptid perhaps, without the need for concentration? If you are in a creepy place you are more likely to think you have seen things as atmosphere affects our emotions. There is no proof either way whether cryptids are real creatures or tulpas but it adds another layer to the world of cryptozoology. Could something like the bigfoot creature have been a tulpa created out of one mind and now seen by others? Tulpas do seem to develop a life and will of their own according to David-Neel. Something more for discussion in the cryptozoology ring and perhaps fuel for the sceptics.