Monsters are monsters are monsters. Big, small, hairy, slimy, finned, clawed, two legs, four legs, or none; unknown to the world, except to those who encounter them. Or are they unknown? Some common animals were once myths.

The giant panda was considered a folk story told by locals but dismissed by Western science until German zoologist Hugo Weigold saw one in 1916.

Zoology considered the North American wood bison extinct until a population of two hundred was stumbled upon in Alberta, Canada, in 1957.

Tribesmen in the Democratic Republic of the Congo claimed a giant ape that killed lions and howled at the moon lived in the Bas-Uele District. This fanciful story of a creature dubbed the Bili Ape was finally validated by science in 1996.

Science is sometimes slow to come around because it needs to be right; gather evidence, observe creatures, and record data. And, legends are just that: legends. Sometimes, however, legends turn out to be true.

The okapi, the megamouth shark, the mountain gorilla: all once considered myths, they are now in textbooks and, in some cases, zoos.

What legends are hidden in the great wide world, slithering, waiting, lurking in the dark?

There are still places on earth never tread by human feet. Let's see what could be out there. Here are six monsters that may exist.

1. Sea Monsters
Oceans are the kind of big that's hard to visualize. Seventy-one percent of the earth is ocean and, although most of it has been satellite mapped, it's estimated ninety-five percent of our waters haven't been explored. We simply don't know what kind of life is down there. When Norwegian adventurer Thor Heyerdahl and colleagues sailed their balsawood raft from Peru to Polynesia in 1947, they saw sea life they couldn't explain. Heyerdahl wrote in his book about the journey, The Kon-Tiki Expedition: By Raft Across the South Seas, that some nights, "balls of light three feet and more in diameter would be visible down in the water, flashing at irregular intervals like electric lights turned on for a moment." What were these lights? They were part of the great unknown.

The coelacanth, a relative of the lungfish and thought extinct for sixty-six million years, was rediscovered in 1938 when a fisherman caught a specimen off the coast of South Africa and showed a museum curator. Not enough for you? Here's something bigger: the eighteen-foot megamouth shark wasn't found until 1976. Let me repeat—it grows up to eighteen feet long.

Anything could come from our oceans. The kraken, the cadborosaurus, the megalodon, a living plesiosaur, Cthulhu, Anything. The giant squid (which grows up to forty-three-feet long) wasn't photographed until 2004. We apparently need to throw out more nets.

2. Thylacine
The thylacine, also called the Tasmanian wolf or Tasmanian tiger, was a real animal. Wait. Was? Or is? It's hard to tell.

This carnivorous marsupial native to Australia, Tasmania, and New Guinea first appeared in the Oligocene Epoch (33.9 million to 23 million years ago) and survived until man decided we didn't want it anymore.

When settlers brought sheep into the thylacine's territories, this apex predator did what apex predators do: it ate them. After the Australian government put a bounty on the beast, it quickly disappeared. The last Tasmanian tiger, Benjamin, died in the Hobart Zoo on Monday, September 7, 1936.

But Benjamin may not be the last. There have been hundreds of sightings in Australia and Tasmania since Benjamin died. In 2015, Greg Booth and his father Joe Booth encountered what they claim was a thylacine while bushwalking. It seemed to be the real deal. They shot grainy video of the beast with a cub and showed it to thylacine researcher Richo Richardson.

"I don't think it's a thylacine. I know it's a thylacine," Richardson told the Tasmanian newspaper The Mercury. "The thylacine exists and I want nothing more than for the species to survive and its welfare looked after."

The thylacine existed for 33.9 million years. Who are we to tell this marsupial wolf it can't anymore?

3. Little People
Stories of diminutive humans are worldwide. Elves of Iceland, Tomtar of Sweden, Kobolds of Germany, Menehune of Hawaii, the Ebu Gogo of Indonesia. These child-sized, human-like creatures have existed for centuries, lurking around humans, teasing us, threatening us, and (in the case of the Ebu Gogo) eating us. The legends of the Ebu Gogo (which means "grandmother who eats anything") were discovered to be real in 2004 when the remains of these small people were discovered on the island of Flores. Why couldn't other legends be true?

Tales of little people that stretch across the United States are eerily similar.

The Wampanoag Indians of Massachusetts have long shared stories of the Pukwudgie. These are three-foot-tall people with large noses and ears. They were jealous of the Wampanoag and took their jealousy out by playing pranks, stealing Wampanoag children, and burning their villages.

The Pukwudgie can become invisible and magically conjure fire. They are also armed with poison arrows and will shoot big people who either blindly wander into Pukwudgie territory or simply annoy them. Pukwudgies have been known to lure people to their deaths in the wilderness.

Similarly, the Delaware Indians tell stories of the Wemategunis. Similar to the Pukwudgie, no one should anger the Wemategunis. These little people will become invisible and use their incredible strength to injure or kill those who have wronged them.

The Sioux, Omaha, and Otoes Indians of South Dakota once feared Spirit Mound, a 1,280-foot-tall hill that is the highest point on the Great Plains within one hundred miles. Two-foot-tall people they called Little Devils lived within the mound and would come out to war with the tribes, killing many with magical arrows. The stories so impressed explorers Meriwether Lewis and William Clark that they detoured their expedition to search for the Little Devils. They didn't find any.

The Shoshone Indian tribe of Wyoming told similar tales of the Nimerigar, a vicious tribe of small people who warred with the Shoshone, mainly using poison arrows.
Maybe, like the Ebu Gogo, someday the remains of one of these arrow-shooting little people will be discovered.

strong>4. Ice Age Animals
In the scope of history, giant mammals lived in the Northern Hemisphere until recent times. Mammoths—large, hairy, lumbering elephant forbearers—wandered across Asia, Africa, North America, and Europe and became extinct around ten thousand years ago. However, a small population remained alive on Wrangel Island, in the Arctic Ocean off Russia, until 1650 B.C. Could other pockets have survived in the far north?

The Lenape, Mohican, and Shawnee tribes speak of the Yakwawiak, or "great bear," huge animals that walked on stiff legs. These tribes today describe the Yakwawiak as mammoths. In 1896, The Portland Press (Maine) published the story of Col. C.F. Fowler, who traveled to Alaska to buy mammoth ivory from Inuit Indians. Some tusks they presented him were bloody with rotted flesh. Fowler asked an elder where the tribesmen got the tusks and he said, "Less than three months before, a party of his young men had encountered a drove of monsters about fifty miles above where he was then encamped, and had succeeded in killing two."

Fowler then found the hunting party and they described the encounter to him: "Their ears were suddenly saluted by a chorus of loud, shrill, trumpet-like calls, and an enormous creature came crashing toward them through the thicket, the ground fairly trembling beneath its ponderous footfalls," Fowler wrote.

Another animal from that era reported in North America is the hyena.
The hyena predecessor Chasmaporthetes, and the hyena-like dog the Borophagus, both called North America home and are thought to have died out in the Ice Age extinction. However, large hyenas have been seen in numerous places across North America, including Arkansas, Montana, and Canada's Northwest Territories.

An anonymous online poster scouting deer with her ex-husband on Lost Mountain in northern Arkansas saw a hyena running with a band of coyotes. "I noticed an animal that wasn't anything like them," the woman claimed. "It had a large hump on its back, legs were sorta low to the ground, and the color was way off. I'd seen them on Discovery Channel enough to know what it was so I started freaking out screaming, 'Oh my God, it's an honest to God hyena.'"

An encounter with a hyena-like beast in Montana in 1886 ended when rancher Israel Ammon Hutchins shot a Shunka Warak'in, which means, "carries off dogs" to the local Native American tribes. Hutchins had the beast mounted; it measures forty-eight inches long, not including the tail, and stands twenty-eight inches tall at the shoulder, according to the Bozeman Daily Chronicle (Montana).

Jack Kirby, Israel Hutchins' grandson, has the specimen in his possession, but is resistant for it to undergo DNA testing.

5. Flying Dinosaurs
Pterosaurs, various species of flying dinosaurs that had wingspans from ten inches to forty-three feet, died in the Cretaceous–Paleogene Extinction (a disaster that claimed seventy-five percent of all life on earth) around sixty-six million years ago.

The pterosaur may not have perished.

Living pterosaurs have been reported from Spain, the Philippines, Indonesia, The Netherlands, Australia, New Guinea, Africa, and South America—and why not? Many beasts survived the extinction: alligators, frogs, birds, turtles, the coelacanth. Why not pterosaurs? Let's look at a few sightings from the United States.

Three elementary school teachers from San Antonio, Texas, drove home from a conference in 1976 when a lizard-skin creature soared over their car on bat-like wings that were about twenty feet across. The teachers all described it as a pterosaur. Teachers should know.

In 1982, a woman in Arkansas, Laura Dean, drove to the store when a huge gray, leathery monster with bat wings flew over her car, according to the Christian County Headliner News. The creature's head had a crest, claws at the tips of its wings, and a rhombus-shaped tail. The beast was about the size of her pickup.

There have also been sightings in Hawaii, North Carolina, and New Mexico. The earth is a big place.

6. Bigfoot
This big, hairy beast is a busy guy. Seen on every continent except Antarctica, in every state except Hawaii, and in every province and territory in Canada, Bigfoot is probably the most commonly encountered mystery creature in the world.

Eyewitnesses have reported Bigfoot (or Sasquatch, Booger, Skunk Ape, etc.) to be anywhere from five feet to ten feet in height. These creatures inhabit woods, plains, and swamps, and sometimes eat trash from bins in the suburbs. Famed primatologist Jane Goodall told NPR in 2002 she thought Bigfoot could be real.

"I'm sure they exist," she said. "Well, I'm a romantic, so I always wanted them to exist. You know, why isn't there a body? I can't answer that, and maybe they don't exist, but I want them to."

The evidence for Bigfoot is great, but then again it isn't. DNA reports from hair, blood, and scat purported to be from Bigfoot usually come back as human, and photographic evidence (except for the highly-debated Patterson-Gimlin film of 1967) tends to be blurry and inconclusive. However, with footprints often highly detailed with dermal ridges; gorilla-like nests found in Bigfoot hotspots; and audio recordings of unknown hoots, howls, and wood knocks, there is some pretty solid proof that something is out there.

All this, plus the sheer number of sightings (dozens each year in the United States alone), puts Bigfoot among the Six Monsters that May Exist.

Conclusion
Between fourteen thousand and eighteen thousand new species of animals, plants, fungi, and microorganisms are discovered each year. An estimated eighty-six percent of the Earth's species haven't yet been discovered, according to National Geographic. Although most of the species found are insects, fungi, and microorganisms, more than four hundred new mammals have been identified since 1993, including new species of orangutan, elephant, and dolphin.

Why not a goblin, or a giant, or a sea monster, or the rediscovery of an animal long thought lost?

Maybe Bigfoot really is out there.