Cryptozoology is, literally, the study of hidden animals. It is the study of such creatures as the Australian bunyips, Bigfoot, the chupacabra, and the Loch Ness monster. It is not a recognized branch of the science of zoology.

Cryptozoology relies heavily upon testimonials and circumstantial evidence in the form of legends and folklore, and the stories and alleged sightings of mysterious beasts by indigenous peoples, explorers, and travelers. Since cryptozoologists spend most of their energy trying to establish the existence of creatures, rather than examining actual animals, they are more akin to psi researchers than to zoologists. Expertise in zoology, however, is asserted to be a necessity for work in cryptozoology, according to Dr. Bernard Heuvelmans, who coined the term to describe his investigations of animals unknown to science.