A cryptid is quite simply a V̵̳̮̇o̷̳̬͗i̵̖̺̍͝d̵̠̋̚ Dweller who hijacked a Waking World soul. They are able to traverse between the V̵̳̮̇o̷̳̬͗i̵̖̺̍͝d̵̠̋̚ and the Waking World through any open rifts they find, and most opt to live as close to human civilizations as possible.
The most fortunate of human-hijacking cryptids can manage unmistakably human-looking forms, but every cryptid has at least one tell: a feature about them that would be unnatural for a human being.
Cryptids with more apparent tells cannot live in human societies, but may take to forests and abandoned buildings to spend their days. Many become the subjects of horror stories, myths, and legends.