The term became particularly well known due to the activities of Alexandra David-Néel (1868-1969) who had sojourned among lamaistic Buddhists in Tibet. The term, as it is generally understood, means an emanation. It is a thought form projected by the individual of a person or animal. David-Néel claimed she had projected one such thought form from her mind after much mental effort. This tulpa manifested itself as a monk. She tells us that it remained seemingly present, but then began to show signs of independence and latterly unpleasantness. She then destroyed it with much mental effort. It is worth noting that she said the tulpa might have been an illusion. It is to be remembered that the altitude of Tibet could have affected her powers of perception.
In cryptozoology, it is sometimes suggested that the human mind can project such forms giving rise to sightings of cryptids. If the cryptid is deemed to be especially unlikely from a zoological point of view, it is suggested it is a tulpa. The term zooform phenomenon has been applied to such an entity by Jonathan Downes.
We cannot be at all certain that tulpas exist, however. If a creature is seen spontaneously, it is unlikely to have been projected by the percipient, as David-Néel could only see her tulpa after strenuous mental effort and, unless the percipient is remarkably psychically talented, he could not project a tulpa with immediate effect.
If tulpas do not exist we must ask how we account for cryptids that are zoological oddities, yet are seen by a plurality of witnesses. To such a question we lack the answer. The powers of suggestion may sometimes apply, particularly if the cryptid is indistinct or distant. The increased possibility of creatures coming through wormholes or portals should not be ignored: such things are not necessarily the stuff of science fiction. For now, we can only speculate.