Fearsome critters are from Lumberjack lore, and were created from oral traditions in logging camps. They were created when woodsmen would sit around a campfire with newcomers to the wilds and they would tell tall tales of strange creatures that lived in the woods. Typically, one man would provide a colorful description of the beast, then another man, equally solemn, would provide a piece of personal experience relating to the creature. They would go on in this way, occasionally answering questions tossed to them from the audience, and they would act so serious that they would convince any newcomers that the critter really does exist and roams the native wilderness. There are many examples of these fearsome critters, some of which include:

The sidehill gouger is a cow-like animal that dwells in the hill country. This fearsome critter goes by many other name like the boofum, the hunkus, the rickaboo, the prock, the sidehill galoot, and many more. They have a special adaption to perfectly suit their hilly habitat, the legs on one side of their body are taller than the legs on the other side. This causes them to walk in a set path, spiraling around the hill. However, this adaption has the unfortunate effect of making them unable to travel across flat fields. If a sidehill gouger with longer left legs comes across a sidehill gouger with longer right legs, they normally fight to the death because they cannot get past the other gouger any other way. Terracettes are said to be created by these beasts. When food is scarce on a sidehill gougers native hill, they often migrate in pairs to a different place. This is done by a right sided gouger swinging its short left legs across a left sided gouger who does the same with their shorter right legs. Using each other as a support, they can migrate to better pastures. Some farmers are said to have bred sideways gougers with their cows in order to make their cows better at grazing on hills. 

Cactus cats are feline creatures with green, spiky hair and long, bony spikes on their elbows. They make their homes inside cactuses, and dwell in the desert. They are addicted to alcohol, and travel in large circles, slicing open cactuses with their elbow spikes. This allows the cactus juices to leak out and the cat moves on to another plant and repeats the process. Their rounds are so large that by the time they return to the first cactuses they had cut open, the juices flowing out had fermented and the cat laps it up. The cat then laps up all the fermented cactus juices until it is so intoxicated that it falls asleep. This feeding process was their downfall unfortunately. Greedy humans would follow after the cats (at a safe distance) and then collect the fermenting cactus juices for themselves. Without their food source, cactus cats are extinct.

The Dunganvenhooter is a crocidilian critter that possesses "Satanic cunning" and enjoys feeding upon intoxicated people wandering the marshlands. The beast appears to be a crocodile with no mouth and large nostrils. It pounds its prey, drunk guys, to a vapor with its tail, and then inhales them through its nose.

A ball tailed cat in a mountain lion like critter with a bulbous tail used for pummeling its prey. Some have spiked tails used for grappling their prey and some have round ones used to knock them unconscious.

goofus birds are birds who build their nests upside down under tree branches and fly backwards because they don't care where they are going, only where they have been.

A rumptifusel is a creature that appears to be a fine fur coat found in the middle of the woods. When a passing lumberjack comes across this fine fur coat, they decide to put it on, and then the coat engulfs them and drains them of their flesh and bones. All that is left behind are little things that are commonly thought to be pellets from owls. This is ridiculous hooey spread by high-falutin scientists but any lumberjack can tell you those are the remains of an unfortunate guy looking for a fine mink pelt.

Ever shot an arrow or bullet at a deer, and missed? Well it obviously wasn't your fault for missing, it was a darn dingbat meddling in human affairs again. Dingbats are cute little fur balls with wings and antlers that snatch bullets right out of the air before they can hit their intended target.

Also, not directly related to fearsome critters but related to mythology and folklore, if you want to read a story that includes somewhat obscure myths and legends, read Hellboy. It is an awesome comic book that has amazing art, stories and characters, all related to mythology brought also has some lovecraftian elements.

Outstanding!

Central and South America does have some great mythology. Though a lot of it is gruesome. Still, other cultures were just as dark. I really like the Aun Pana. They are evil fish monsters covered in hair and they have long arms they use to drag people to the bottom of rivers and drown them. They once waited for a hunting party to cross a big bridge and then destroyed the bridge as they were on it. The aun pana then begain drowning the people, but a few started to escape by grabbing onto flotsam and clambering ashore. Enraged by the thought of their victims escaping the aun pana chieftain transformed the people into monkeys and boars as they tried to escape. They fled back to the village, but since the villagers saw a bunch of animals running straight towards them and they were eaten.

There was also the mapinguari which was a horrible giant sloth like monster with one-eye, backwards claws, and a toothy maw on their stomach. 

Then there was the ahuizotl, an aquatic dog-like beast with a clawed hand on its tail which it used to drown people who came to close the edge of the river. They ate the victims teeth, fingernails, and eyes, and then let the rest of the corpse float to the surface of the river.

Sorry, once I get started I find it hard to stop.

*there. 

How bout Celt mythology. Like, the druids and such. 

Also, a somewhat obscure Greek and Roman creature, the Astomi are a people group who survive by smelling rather than eating. They lack mouths, and have rough and hairy bodies. They carry apples, roots, and flowers with them when the travel in order to inhale sustenance from them. They can die from smelling a scent that is too strong, and they also have no need to drink. I might make this a character race just for fun. But they can't speak normally because they have no mouths, so that would be a problem.

What about Celtic mythology? It is cool and has many awesome things that could easily be put in Dnd.

Like there was this fey spirit that took the form of a bard every couple of years and would go to a certain kingdom every couple of years, bringing doom and destruction. They would call on the kings hospitality to get into the castle walls, and then magically put the guards to sleep to get into the hall where the king was with his guests. He would then play music and all the people would fall asleep. The Bard would then go throughout the kingdom breathing fire and burn the whole place down. This was a big problem, so a hero (I forget his name) came and placed a spear in a uncomfortable position so that when the evil fey bard tried to put him to sleep, the spear would poke him and he would awaken. He then killed the bard and rescued the kingdom. Some people fight fire breathing dragons, he fought fire breathing minstrels. 

That’s fun!

What do y’all know about Navajo witches/Skinwalkers?

Not much other than they are Native American shapeshifting witches that possess, transform into or wear the skin of an animal and then transform into it.

What do you know about them?

Mostly stuff I’ve reas in To y Hillerman novels. 

They possess the power to turn into a wolf (and sometimes a couple other things). They’re very hard to kill, and very dangerous. I can’t remember much more about their capabilities at the moment, but you become one by committing a taboo such as (tw here) incest, or just being so dang evil that you turn into one. 

What did To y Hillerman write?

Quote from The_Summoning_Dark >>

What did To y Hillerman write?

 

 Tony Hillerman wrote a bunch of mystery novels, the protagonist of which is a Navajo policeman who had been training to become a shaman. It deals with a lot of the superstitions and myths of the Navajo. 

a great one to start on is Skinwalkers. 

Sounds interesting. If you want another book that includes great references to mythology, I highly recommend N. D. Wilson. He is probably my favorite author, and I have read Tolkien, Terry Pratchett, Frank Herbert, Christopher Paolini, and others like them. His books are similar to Rick Riordan's books if Riordan's books were well written and had more obscure mythology. He has written the 100 Cupboards series, and the Ashtown Burials series. They are amazing and I cannot recommend his books enough.

Cool! I might have to check them out. 

So, Skinwalkers are a very specific kind of being, tied deeply to the nature of Dineh custom and mores.

as noted, they arise from breaking taboo, and the deep secret is that they can take the skin of any being, devouring them, and replacing them — wearing their skin as they commit heinous deeds.

Skinwalkers are generally classified as bogeymen, but I think they fall closer to vampires (in terms of global lore, not game or novel stuff).

taboos include not performing rituals properly, theft of a house, drinking too much, murder in rage, and cowardice.

they are rare, and keep themselves hidden, disguised, because the duty of a warrior is to kill on sight.

Rebecca Roanhorse did a two book series that has some interesting use of Dineh folklore

Nice, what are the names of those books?

Storm of Locusts, Trail of Lightning

All of the following come from folklore, though details are changed like name, but I did use the descriptions:

Bloodvine

The greatest horror is the vine which they call "the devil's snare", and we’re full of stories of its death-dealing powers. I was able to discover truly little about the nature of the plant, owing to the difficulty of handling it, for its grasp can only be torn away with the loss of skin and even of flesh; but, as near as my friend Dunstan could ascertain, its power of suction is contained in several infinitesimal mouths or little suckers, which, ordinarily closed, open for the reception of food. If the substance is animal, the blood is drawn off and the carcass or refuse then dropped. This does make it easy to avoid, if you can spot the skeletons that the vines tend to cover or catch the scent of death in the air.

Devilpops

These are parasitic vines with purple blossoms known as the "devil's poppy" that seize and poison animals. Is a potent narcotic. My band once fell asleep passing through a meadow full of the damn things. Lost my dog, Toto, too.

Madagar Tree

The slender delicate palpi, with the fury of starved serpents, quivered a moment over her head, then as if instinct with demoniac intelligence fastened upon her in sudden coils round and round her neck and arms; then while her awful screams and yet more awful laughter rose wildly to be instantly strangled down again into a gurgling moan, the tendrils one after another, like great green serpents, with brutal energy and infernal rapidity, rose, retracted themselves, and wrapped her about in fold after fold, ever tightening with cruel swiftness and savage tenacity of anacondas fastening upon their prey. I still have scars from this damn thing. I won’t say where.

Yateveo

Named for producing a hissing sound and having poisonous "spines" that resemble "many huge serpents in an angry discussion, occasionally darting from side to side as if striking at an imaginary foe" which seize and pierce any creature coming within reach.

Are those plants from mythology? Where are they from?

Been a while but...

The underlying bloodvine myth was used in Harry Potter, but is the vampire vine of legend from Nicaragua.

Devil pops is actually a full on take of the opium flower and its introduction to the west. Disguised as a reference to the Wizard of Oz, where they were used on film.

The madagar tree is from an African source (Madagascar).

The yataveo  is a well known man eating tree myth about,  well, africa and South America.  It was used in the resident evil game, oddly enough.

Of course, the daffodil is a famous mythical plant: it was called narcissus and has an entire greek myth about it.

Irish mythology has grass that is is hungry (hungry grass), slavic lore has the lucky fern flower, and the nearby balkans have the vampire pumpkin (seriously, lol).