Cryptozoology is a pseudoscience and subculture that searches for and studies unknown, legendary, or extinct animals whose present existence is disputed or unsubstantiated, particularly those popular in folklore, such as Bigfoot, the Loch Ness Monster, Yeti, the chupacabra, the Jersey Devil, or the Mokele-mbembe. Cryptozoologists refer to these entities as cryptids, a term coined by the subculture. Because it does not follow the scientific method, cryptozoology is considered a pseudoscience by mainstream science: it is neither a branch of zoology nor of folklore studies. It was originally founded in the 1950s by zoologists Bernard Heuvelmans and Ivan T. Sanderson.

Scholars have noted that the subculture rejected mainstream approaches from an early date, and that adherents often express hostility to mainstream science. Scholars studying cryptozoologists and their influence (including cryptozoology's association with Young Earth creationism) noted parallels in cryptozoology and other pseudosciences such as ghost hunting and ufology, and highlighted uncritical media propagation of cryptozoologist claims.

As a field, cryptozoology originates from the works of Bernard Heuvelmans, a Belgian zoologist, and Ivan T. Sanderson, a Scottish zoologist. Notably, Heuvelmans published On the Track of Unknown Animals (French: Sur la piste des bêtes ignorées) in 1955, a landmark work among cryptozoologists that was followed by numerous other similar works. In addition, Sanderson published a series of books that contributed to the developing hallmarks of cryptozoology, including Abominable Snowmen: Legend Come to Life (1961). Heuvelmans himself traced cryptozoology to the work of Anthonie Cornelis Oudemans, who theorized that a large unidentified species of seal was responsible for sea serpent reports.

Cryptozoology is 'the study of hidden animals' (from Ancient Greek: κρυπτός, kryptós "hidden, secret"; Ancient Greek ζῷον, zōion "animal", and λόγος, logos, i.e. "knowledge, study"). The term dates from 1959 or before— Heuvelmans attributes the coinage of the term cryptozoology to Sanderson. Following cryptozoology, the term cryptid was coined in 1983 by cryptozoologist J. E. Wall in the summer issue of the International Society of Cryptozoology newsletter. According to Wall "[It has been] suggested that new terms be coined to replace sensational and often misleading terms like 'monster'. My suggestion is 'cryptid', meaning a living thing having the quality of being hidden or unknown ... describing those creatures which are (or may be) subjects of cryptozoological investigation."

The Oxford English Dictionary defines the noun cryptid as "an animal whose existence or survival to the present day is disputed or unsubstantiated; any animal of interest to a cryptozoologist". While used by most cryptozoologists, the term cryptid is not used by academic zoologists. In a textbook aimed at undergraduates, academics Caleb W. Lack and Jacques Rousseau note that the subculture's focus on what it deems to be "cryptids" is a pseudoscientific extension of older belief in monsters and other similar entities from the folkloric record, yet with a "new, more scientific-sounding name: cryptids".

During post-production of the Champ, (America's Loch Ness), movie Lucy and the Lake Monster, the filmmakers reviewed their drone footage from production on August 2, 2024, and noticed what appears to be a large creature swimming just below the surface of the water, in Bulwagga Bay. The alleged plesiosaur image is visible in the bottom right portion of the screen, swimming behind a boat containing the two lead actors in the film. The boat was 142 inches from the tip of the bow to the stern and 50.5 inches at the widest point and the alleged plesiosaur appears bigger than the boat.

One of the co-writers, Kelly Tabor, a cryptozoology adherent who has searched for the legendary sea serpent of Lake Champlain for fifty years, believes it is probably Champ. The second co-writer and director of the film, Richard Rossi, referred to himself as the "Doubting Thomas," and was concerned that the cryptozoology folklore around Champ was pseudoscience and that cryptozoologists enthused about the drone discovery did not have legitimate earned academic degrees in science. Rossi shared the entire five minutes of footage with scientists with earned doctorates in science for further study to prepare a scholarly article for academic peer review. A five-second clip from the longer five minute footage was shared publicly on YouTube.

While biologists regularly identify new species, cryptozoologists often focus on creatures from the folkloric record. Most famously, these include the Loch Ness Monster, Champ (folklore), Bigfoot, the chupacabra, as well as other "imposing beasts that could be labeled as monsters". In their search for these entities, cryptozoologists may employ devices such as motion-sensitive cameras, night-vision equipment, and audio-recording equipment. While there have been attempts to codify cryptozoological approaches, unlike biologists, zoologists, botanists, and other academic disciplines, however, "there are no accepted, uniform, or successful methods for pursuing cryptids". Some scholars have identified precursors to modern cryptozoology in certain medieval approaches to the folkloric record, and the psychology behind the cryptozoology approach has been the subject of academic study.

Few cryptozoologists have a formal science education, and fewer still have a science background directly relevant to cryptozoology. Adherents often misrepresent the academic backgrounds of cryptozoologists. According to writer Daniel Loxton and paleontologist Donald Prothero, "[c]ryptozoologists have often promoted 'Professor Roy Mackal, PhD.' as one of their leading figures and one of the few with a legitimate doctorate in biology. What is rarely mentioned, however, is that he had no training that would qualify him to undertake competent research on exotic animals. This raises the specter of 'credential mongering', by which an individual or organization feints a person's graduate degree as proof of expertise, even though his or her training is not specifically relevant to the field under consideration." Besides Heuvelmans, Sanderson, and Mackal, other notable cryptozoologists with academic backgrounds include Grover Krantz, Karl Shuker, and Richard Greenwell.

Historically, notable cryptozoologists have often identified instances featuring "irrefutable evidence" (such as Sanderson and Krantz), only for the evidence to be revealed as the product of a hoax. This may occur during a closer examination by experts or upon confession of the hoaxer.

Cryptozoologists have often led expeditions to find evidence of their claims. Bigfoot researcher René Dahinden led unsuccessful expedition into caves to find evidence of sasquatch, which Daniel Loxton attributes to changes in the popular perception of bigfoot. Lensgrave Adam Christoffer Knuth led an expedition into Lake Tele in the Congo to find the Mokele-mbembe in 2018. While they found no evidence of the creature, they did find a new species of green algae.

A subset of cryptozoology promotes the pseudoscience of Young Earth creationism, rejecting conventional science in favor of a literal Biblical interpretation and promoting concepts such as "living dinosaurs". Science writer Sharon A. Hill observes that the Young Earth creationist segment of cryptozoology is "well-funded and able to conduct expeditions with a goal of finding a living dinosaur that they think would invalidate evolution".

Anthropologist Jeb J. Card says that "[c]reationists have embraced cryptozoology and some cryptozoological expeditions are funded by and conducted by creationists hoping to disprove evolution." In a 2013 interview, paleontologist Donald Prothero notes an uptick in creationist cryptozoologists. He observes that "[p]eople who actively search for Loch Ness monsters or Mokele Mbembe do it entirely as creationist ministers. They think that if they found a dinosaur in the Congo it would overturn all of evolution. It wouldn't. It would just be a late-occurring dinosaur, but that's their mistaken notion of evolution."

Citing a 2013 exhibit at the Petersburg, Kentucky-based Creation Museum, which claimed that dragons were once biological creatures who walked the earth alongside humanity and is broadly dedicated to Young Earth creationism, religious studies academic Justin Mullis notes that "[c]ryptozoology has a long and curious history with Young Earth Creationism, with this new exhibit being just one of the most recent examples".

Academic Paul Thomas analyzes the influence and connections between cryptozoology in his 2020 study of the Creation Museum and the creationist theme park Ark Encounter. Thomas comments that, "while the Creation Museum and the Ark Encounter are flirting with pseudoarchaeology, coquettishly whispering pseudoarchaeological rhetoric, they are each fully in bed with cryptozoology" and observes that "[y]oung-earth creationists and cryptozoologists make natural bed fellows. As with pseudoarchaeology, both young-earth creationists and cryptozoologists bristle at the rejection of mainstream secular science and lament a seeming conspiracy to prevent serious consideration of their claims."

Media outlets have often uncritically disseminated information from cryptozoologist sources, including newspapers that repeat false claims made by cryptozoologists or television shows that feature cryptozoologists as monster hunters (such as the popular and purportedly nonfiction American television show MonsterQuest, which aired from 2007 to 2010). Media coverage of purported "cryptids" often fails to provide more likely explanations, further propagating claims made by cryptozoologists.

There is a broad consensus among academics that cryptozoology is a pseudoscience. The subculture is regularly criticized for reliance on anecdotal information and because in the course of investigating animals that most scientists believe are unlikely to have existed, cryptozoologists do not follow the scientific method. No academic course of study nor university degree program grants the status of cryptozoologist and the subculture is primarily the domain of individuals without training in the natural sciences.

Anthropologist Jeb J. Card summarizes cryptozoology in a survey of pseudoscience and pseudoarchaeology:

Cryptozoology purports to be the study of previously unidentified animal species. At first glance, this would seem to differ little from zoology. New species are discovered by field and museum zoologists every year. Cryptozoologists cite these discoveries as justification of their search but often minimize or omit the fact that the discoverers do not identify as cryptozoologists and are academically trained zoologists working in an ecological paradigm rather than organizing expeditions to seek out supposed examples of unusual and large creatures.

Card notes that "cryptozoologists often show their disdain and even hatred for professional scientists, including those who enthusiastically participated in cryptozoology", which he traces back to Heuvelmans's early "rage against critics of cryptozoology". He finds parallels with cryptozoology and other pseudosciences, such as ghost hunting and ufology, and compares the approach of cryptozoologists to colonial big-game hunters, and to aspects of European imperialism. According to Card, "[m]ost cryptids are framed as the subject of indigenous legends typically collected in the heyday of comparative folklore, though such legends may be heavily modified or worse. Cryptozoology's complicated mix of sympathy, interest, and appropriation of indigenous culture (or non-indigenous construction of it) is also found in New Age circles and dubious "Indian burial grounds" and other legends [...] invoked in hauntings such as the "Amityville" hoax [...]".

In a 2011 foreword for The American Biology Teacher, then National Association of Biology Teachers president Dan Ward uses cryptozoology as an example of "technological pseudoscience" that may confuse students about the scientific method. Ward says that "Cryptozoology [...] is not valid science or even science at all. It is monster hunting." Historian of science Brian Regal includes an entry for cryptozoology in his Pseudoscience: A Critical Encyclopedia (2009). Regal says that "as an intellectual endeavor, cryptozoology has been studied as much as cryptozoologists have sought hidden animals".

In a 1992 issue of Folklore, folklorist Véronique Campion-Vincent says:

Unexplained appearances of mystery animals are reported all over the world today. Beliefs in the existence of fabulous and supernatural animals are ubiquitous and timeless. In the continents discovered by Europe indigenous beliefs and tales have strongly influenced the perceptions of the conquered confronted by a new natural environment. In parallel with the growing importance of the scientific approach, these traditional mythical tales have been endowed with sometimes highly artificial precision and have given birth to contemporary legends solidly entrenched in their territories. The belief self-perpetuates today through multiple observations enhanced by the media and encouraged (largely with the aim of gain for touristic promotion) by the local population, often genuinely convinced of the reality of this profitable phenomenon."

Campion-Vincent says that "four currents can be distinguished in the study of mysterious animal appearances": "Forteans" ("compiler[s] of anomalies" such as via publications like the Fortean Times), "occultists" (which she describes as related to "Forteans"), "folklorists", and "cryptozoologists". Regarding cryptozoologists, Campion-Vincent says that "this movement seems to deserve the appellation of parascience, like parapsychology: the same corpus is reviewed; many scientists participate, but for those who have an official status of university professor or researcher, the participation is a private hobby".

In her Encyclopedia of American Folklore, academic Linda Watts says that "folklore concerning unreal animals or beings, sometimes called monsters, is a popular field of inquiry" and describes cryptozoology as an example of "American narrative traditions" that "feature many monsters".

In his analysis of cryptozoology, folklorist Peter Dendle says that "cryptozoology devotees consciously position themselves in defiance of mainstream science" and that:

The psychological significance of cryptozoology in the modern world [...] serves to channel guilt over the decimation of species and destruction of the natural habitat; to recapture a sense of mysticism and danger in a world now perceived as fully charted and over-explored; and to articulate resentment of and defiance against a scientific community perceived as monopolising the pool of culturally acceptable beliefs.

In a paper published in 2013, Dendle refers to cryptozoologists as "contemporary monster hunters" that "keep alive a sense of wonder in a world that has been very thoroughly charted, mapped, and tracked, and that is largely available for close scrutiny on Google Earth and satellite imaging" and that "on the whole the devotion of substantial resources for this pursuit betrays a lack of awareness of the basis for scholarly consensus (largely ignoring, for instance, evidence of evolutionary biology and the fossil record)."

According to historian Mike Dash, few scientists doubt there are thousands of unknown animals, particularly invertebrates, awaiting discovery; however, cryptozoologists are largely uninterested in researching and cataloging newly discovered species of ants or beetles, instead focusing their efforts towards "more elusive" creatures that have often defied decades of work aimed at confirming their existence.

Paleontologist George Gaylord Simpson (1984) lists cryptozoology among examples of human gullibility, along with creationism:

Humans are the most inventive, deceptive, and gullible of all animals. Only those characteristics can explain the belief of some humans in creationism, in the arrival of UFOs with extraterrestrial beings, or in some aspects of cryptozoology. [...] In several respects the discussion and practice of cryptozoology sometimes, although not invariably, has demonstrated both deception and gullibility. An example seems to merit the old Latin saying 'I believe because it is incredible,' although Tertullian, its author, applied it in a way more applicable to the present day creationists.

Paleontologist Donald Prothero (2007) cites cryptozoology as an example of pseudoscience and categorizes it, along with Holocaust denial and UFO abductions claims, as aspects of American culture that are "clearly baloney".

In Scientifical Americans: The Culture of Amateur Paranormal Researchers (2017), Hill surveys the field and discusses aspects of the subculture, noting internal attempts at creating more scientific approaches and the involvement of Young Earth creationists and a prevalence of hoaxes. She concludes that many cryptozoologists are "passionate and sincere in their belief that mystery animals exist. As such, they give deference to every report of a sighting, often without critical questioning. As with the ghost seekers, cryptozoologists are convinced that they will be the ones to solve the mystery and make history. With the lure of mystery and money undermining diligent and ethical research, the field of cryptozoology has serious credibility problems."

There have been several organizations, of varying types, dedicated or related to cryptozoology. These include:

• International Fortean Organization – a network of professional Fortean researchers and writers based in the United States
• International Society of Cryptozoology – an American organisation that existed from 1982 to 1998
• Kosmopoisk – a Russian organisation whose interests include cryptozoology and Ufology
• The Centre for Fortean Zoology- an English organization centered around hunting for unknown animals

The zoological and cryptozoological collection and archive of Bernard Heuvelmans is held at the Musée Cantonal de Zoologie in Lausanne and consists of around "1,000 books, 25,000 files, 25,000 photographs, correspondence, and artifacts".

In 2006, the Bates College Museum of Art held the "Cryptozoology: Out of Time Place Scale" exhibition, which compared cryptozoological creatures with recently extinct animals like the thylacine and extant taxa like the coelacanth, once thought long extinct (living fossils). The following year, the American Museum of Natural History put on a mixed exhibition of imaginary and extinct animals, including the elephant bird Aepyornis maximus and the great ape Gigantopithecus blacki, under the name "Mythic Creatures: Dragons, Unicorns and Mermaids".

In 2003, cryptozoologist Loren Coleman opened the International Cryptozoology Museum in Portland, Maine. The museum houses more than 3000 cryptozoology related artifacts.

• Ethnozoology
• Fearsome critters, fabulous beasts that were said to inhabit the timberlands of North America
• Folk belief
• List of cryptids, a list of cryptids notable within cryptozoology
• List of cryptozoologists, a list of notable cryptozoologists
• Scientific skepticism

• Media related to Cryptozoology at Wikimedia Commons