Courtesy of: http://www.newanimal.org/
In folklore, werewolves are people who sometimes shapeshift into wolves. Because werewolves are usually thought to be part of the supernatural, they are seldom investigated by people working in the field of cryptozoology. After all, cryptozoologists are trying to discover new species of animal to be accepted by the mainstream scientific establishment, not resurrect mythical beasts. And werewolves seem to be about as far to the mythical side as beasts can get.
However, a certain number of sightings of wolf-like hairy humanoids are reported to cryptozoologists, and some of these sightings are so well-documented that they are taken seriously by those who are investigating them. Once these reports are taken seriously, they need some kind of explanation. Some of these reports describe unusually intelligent, odd-looking wolves who like to walk around on their hind legs. Other reports describe hairy humanoids that sound like Bigfoot, except that the head is described as looking like a wolf.
The reports come from a wide variety of people, including those who are grounded in a cultural tradition that accepts the idea that werewolves might exist and those who are not grounded in such a tradition. In other words, these sightings are not limited to heavily traditional ethnic groups. However, the exact features described do tend to vary according to cultural patterns. For example, a sighting made in the southwestern United States by a Navajo is likely to conform to skinwalker lore, but a sighting from nearly the same area made by a person of Hispanic ancestry will tend to includes features from the brujo, or Mexican witch.
For those cryptozoologists who don’t simply dismiss “werewolf” sightings as being too silly to look into, there are two main kinds of explanation put forth for what these werewolf-like creatures could actually represent. Some researchers think that these sightings may represent a hidden species of hyper-intelligent wild dogs that evolved to become bipedal and therefore, these dogs coincidentally ended up looking something like a cross between a person and a wolf. Other researchers try to classify these cryptids as a subcategory of Bigfoot with long snouts and pointed ears, or as sightings of Bigfoot where the witnesses panicked so much that they superimposed werewolfish features on what was actually an ordinary Bigfoot.
Beyond these two main explanations, there are also a number of minor ones. Only a few cryptozoologists think that werewolves are actually people who can shapeshift into wolves, because it is hard to think of a scientific, biological explanation for shapeshifting that doesn’t involve dozens of absurdities. The few researchers working in fringe cryptozoology who actually believe in shapeshifting tend to ascribe this power to aliens in one way or another, either by saying that werewolves are actually aliens masquerading as human, or by saying that werewolves are the result of alien experiments on human beings.
There is also the idea, widespread in fringe cryptozoology, that most hard-to-explain creatures are actually visitors from some parallel dimension of reality, and this idea is sometimes applied to reports of lupine hairy humanoids. In this scenario, “werewolves” are generally thought of as animalistic humanoids that are native to some alternate reality. Which also neatly dispenses with the need for physical evidence, as any dead body is supposed to return to its native plane of existence.
However you want to explain it, it seems that werewolf sightings just refuse to completely die out. There are many nonfiction books about werewolf lore and fairy tales that I won’t bother to list below; the sources cited below are works that concentrate to some extent on modern superstitions or beliefs about werewolves, such as the series of reports from southeastern Wisconsin made by many witnesses who claimed to have seen the creature called the Beast of Bray Road.