Indeed, rabbits are an actual example. With those teeth, they can inflict quite a bit of damage, and rabbits are hardly docile creatures. Male rabbits will rape so that they can breed like rabbits, and castrate rival males to ensure their own breeding rights. Yeah. Rabbits castrate each other with no anaesthesia. They also headbutt, and their kicks pack quite a bit of power for their size, to the point that they can break their own spine if they kick hard enough. Some rabbits are known to attack snakes. One gained fame for trying to board Jimmy Carter's fishing boat in 1979. It even was nicknamed "Killer Rabbit" by the media.
The prehistoric Bullockornis resembles a human-sized duck. With a viciously sharp beak and a carnivorous appetite, the demon duck of doom makes Velociraptor look like an adorable bunny in comparison.
Speaking of which, Velociraptor itself is an example of this trope. Even when it doesn't look like the one in Jurassic Park, a coyote-sized, feathery chicken-like dinosaur is perfectly capable of taking on a full-grown Protoceratops.
Domesticated dogs and cats still have hunter's instincts, and will often attack small animals they come across even if they're not hungry. Cats in particular, due to their mobility and stealthiness, are well equipped to hunt down various small animals such as birds and rodents that might be lurking in your back yard. Because they don't need the food, cats will often just play with their catches rather than eat them. For an added bonus, cats have a lot of bacteria in their mouths, which can make their bites surprisingly nasty - second only to that of a human being, in terms of infectiousness. (If you are bit by a cat, go get medical treatment!!) Cats were largely domesticated because their ancestors' presence was tolerated due to them being very good at pest control, which became extremely important around 10,000 years ago when humans decided to settle down and take up agriculture.
Koalas. It's not hard to piss them off, especially if you interrupt one of their 19 hours of sleep, and they have huge teeth and claws that can do some real damage when you rile them up. Please stay away from them. Fun fact: they are always POed at you because they're coming down from a high. Eucalyptus leaves actually contain a mild toxin, to which they have built up a resistance that instead makes them stoned. Hence the sleeping 19 hours a day.
Wombats can do a fair amount of damage too - one naturalist ended up with a 2cm deep bite in his leg. Through a gumboot, trousers, and thick socks. And if they get some speed up (40km/hr at maximum, despite being generally slow) they can knock grown men over. This being Australia, their main defence against predators is to hide in a hole and use their cartilage-heavy, armour-plated arse to keep themselves from serious harm — and their modified pelvic bone that forms the aforementioned armor-plating is sturdy enough to crush a dingo's skull, if one manages to get its head into the hole before it's completely blocked off. Australia is potholed to Death World for a reason.
There's been instances of cars hitting wombats and flipping over. The wombat was fine. The car? Not so much.
The platypus looks like an adorable beaver-duck, but the poisonous stinger of the males contains one of the nastier venoms known to man. It causes immediate hyperalgesia in humans, which is acute hypersensitivity to pain that can't be dulled by painkillers and can last weeks to months. Yikes!
In other words: it won't kill you, but it will make you wish that it did.
Pain-killers technically can dull it, but the dosage is so high you will almost certainly die from it.
Due to causing vehicular accidents, the deadliest animal in the USA is the deer. Moose are even worse. Think you're safe in your two-ton cage of speeding metal? Think again! Hitting a deer or moose can easily cause a fatal accident. Moose legs are also uniquely suited to slide up a car hood and through the windshield in a collision.
Not to mention their antlers, sharp hooves, and teeth. An annoyed horse will just bite your hand really hard then let go, to tell you stay away. A deer that thinks you're trying to kill it, however, bites your hand then tries to rip your hand off.
Red deer regularly devour birds, rodents and even smaller deer.
While emus don't fall under the generally accepted category of "cute", they are essentially human sized birds with fluffy feathers and big, expressive eyes. They can also kick you to death in a matter of seconds. Most of those tall, long-legged, flightless birds aren't that harmless. Ostriches are reputed to be able to disembowel a lion.
The emu's relative the Cassowary is essentially a Velociraptor with a beak. Also, Eye Scream, they are attracted to shiny objects, like human eyes. Which are at beak level. The cassowary, a rather silly-looking◊ flightless bird best known for having an oddly-shaped head, also sports a set of claws that make it pretty much the closest modern-day equivalent of a velociraptor◊. If you manage to piss one off, it can and will eviscerate you, and there are numerous cases of death-by-cassowary on record. They have been known to eat metal.
The blue-ringed octopus. Not exactly cute, but it definitely wouldn't look very threatening, despite being one of the most poisonous sea creatures known to man. As comedian Billy Connolly says "It wouldn't fit in the palm of your hand, but if this thing's in a bad mood you don't make it to the *** phone!"
Octopi are mostly known as tiny and occasionally even cute little animals that have amazing abilities of fitting into the smallest cracks and change their skin to match any surface. So when the staff of a marine aquarium decided to move their North Pacific Giant Octopus into a tank with their sharks, they didn't expect it to have any trouble staying safe. And then each night more and more of the sharks were disappearing or found dead.
Mustelids (ferrets, minks, weasels, martens, sables, badgers and wolverines) are unbelievably strong for their size. They are not afraid to fight back fiercely when threatened by greater predators, despite their cute, fluffy appearance. There's a reason why badger is a verb and Wolverine is a superhero.
It should be noted, though, that the European Badger is a shy social animal (they live in small family groups) that prefers to avoid confrontation and will only fight back when it is unable to escape. The badger's dubious reputation as a feriocious animal actually comes from the old "sport" of "Badger Baiting". Which, sadly, pretty much consisted of trapping a badger and forcing it to fight to the death against hunting dogs.
The badger's reputation of reluctant ferocity and toughness is well deserved. Their skulls and hides are incredibly thick, and layered with tough muscle that makes them highly resistant to 'cudgels, blades, and shot' according to monographs from periods when they were hunted. In addition, their burrowing claws are capable of doing massive damage. Oh, and that thick skull? Its built in such a way that once a badger locks into a bite it must be dislodged with crowbars. Post-mortem. Beware the Nice Ones indeed.
And then there's the Honey Badger, their more irritable African cousin. The honey badger is kinda cute, but it has thick, tough skin that acts as some sort of body armor, giving it some protection against the claws of large animals such as lions. Its skin is too thick for the fangs of venomous snakes to penetrate, so it can eat those. It sometimes attacks (small) crocodiles. There's a reason "Honey badger don't care" became a meme.
These things have been know to chase off, if not kill full grown lions. How? it uses its small size and speed to run right under the lion, and try to rip its balls off. Also, these little guys will growl, hiss and charge at their attackers to frighten them away. And, if that doesn't work? They produce a rather foul smell from their behinds, much like skunks. And, yes, it's quite effective in driving predators away. Oh, and the name? Comes from the fact that they really like honey, how does it get said honey? By shoving its face into an occupied bee hive and chowing down while ignoring the bees protests, and keep in mind, these are African honey bees, aka the granddaddies of Killer Bees.
They're also very smart, being one of the few animals that have been documented using tools; a Honey Badger was filmed using a log to help it reach a small bird that was tangled in some vines.
The Giant Panda. Another contender for "cutest bear" (it is a card-carrying member of the bear family, as shown by molecular genetics), a truly ridiculous amount of time, effort, and money has gone into saving these fat and lazy animals. Some people might think pandas are vegetarians because they only eat bamboo. They only eat bamboo because it's one of the only things that can't outrun them, being plants. Give an adult 200 pound panda a chance, and it will kill and eat small animals, possibly including children. Fun fact: Pandas actually have a carnivore digestive system. Its round face is the result of powerful jaw muscles, which attach from the top of the head to the jaw.
A National Geographic article once told about a panda named Zhen Zhen who terrorized a camp, demolishing tents and attacking people.
A article in the London newspaper Metro involved a viper that was rescued from a house in China. The rescuers tried to feed it a live mouse and the mouse killed it after a half-hour struggle. They could only theorise it had run out of venom during the capture.
Raccoons, anyone? They look like fuzzy little puppy-cat things with domino masks, but their teeth and claws can kill pets and send people to the emergency room. To top it off, they're the biggest carrier of rabies in North America (though domestic dogs are the biggest rabies vector in general). That's not mentioning the fact that they also tend to have really, really nasty tempers and utterly zero fear of humans.
Popular perception of dolphins pictures them as happy and cheerful, but their bodies have more than enough strength to severely hurt and even kill sharks and humans, two species of badass apex predators. Dolphins also tend to torture their prey before killing them. And then there are the bottlenose dolphins, which could very well be described as Flipper's evil twin. Also, dolphins will try to fuck Anything That Moves, and will rape you if they get half a chance. Think twice about their smile.
There are some tree frogs, small and rather beautiful. And whether they are alive or dead, merely touching them with one's bare skin is a bad idea. With a tip of blowgun dart, on the other hand.... Fortunately, the ones in captivity are not fed the ants that cause them to produce said toxins.
Shrews are fuzzy and tiny, which is a recipe for textbook cuteness. Gram for gram, they're also the most voraciously-bloodthirsty predators on the planet, killing prey many times their own size and eating anything that moves, and consuming triple their body weight daily. Some of them have venomous saliva as well, so be glad these things are so little.
Chimpanzees. Most funny and human among the whole lot of funny monkeys, right? In reality they are insanely strong (a 70 kg male can lift up to 300 kg; less surprising when you take a look at those muscles◊) and very dangerous when pissed off. Some have killed adult people and even kidnapped and eaten human babies. Intra-species murder, wars between bands, and even cannibalism aren't unknown in them either. And yet people still think worse of the comparatively harmless gorilla...
Pigs are generally thought of as ugly, fat, listless, and generally harmless creatures... unless you are a pig farmer. Editor has been told that a farmer being trampled (and subsequently eaten) is not unheard-of.
Modern swine are much more docile than their Iron Age ancestors, which were more like barely tamed boar. In Ancient Rome, pig farming was infamous for the extreme danger involved.
Perhaps best illustrated by the attitude of the veterinary profession. Cows that can kick and gore and break bones? Stocks, tranquilizer, good to go. Horses that can do the same? Experienced equestrian, tranquilizer, no problem. Sheep? Pshh, sit 'em on their rumps, end of problem. Pigs? WE NEED LOTS OF DRUGS AND HALF A DOZEN NURSES AND A FARMER WITH A METAL CATCHPOLE AND A REALLY STURDY METAL PEN AND EXCELLENT EARPLUGS AND IF I DON'T MAKE IT OUT HERE'S MY WILL.
While Bulls are already perceived for being badasses, Cows aren't that much far behind in that regard.
Squirrels are cute, nervous, and fuzzy. Harmless, right? Or are they arboreal piranhas?
The Cone Snail. Many people pick them up because they're pretty... and get a deadly neurotoxic harpoon stuck right into them! Due to the speed at which the snail fires the harpoon, they are actually the fastest snails on earth.
From the right perspective, jellyfish can look like gracefully-flowing gossamer, living chandeliers. But one touch and you'll know what days of agony is like if you're lucky; if not, and it's one of the nastier species, you'll learn what a few minutes of agony and the afterlife are like.
Man-o-wars. Look like jellyfish but are really a colony of different organisms where one is a purple floating sac and the rest are tentacles that make digestion and attack. From outside the water, it looks beautiful◊. Under the water, they are goddamn painful and, in some cases, can kill a person.
Chow Chows basically just look like big balls of fluff, but they have a reputation for being aggressive - to the point that the words "chow" or "chow mix" are basically code for "be on your guard" in your average veterinary clinic.
Pit Bulls and Rottweilers go for your limbs, to hurt you. Chows go for your throat to go for the kill.
Sloths. They're big, sleepy, slow-moving critters... living in jungles. Y'know, where EVERYTHING tries to eat you. Think about that for a second.
The sloth's ancestors were roughly the size of elephants and could basically do whatever the fuck they wanted without having to fear predators.
Anteaters don't even have teeth, but they've got claws to compensate. And if you ever see one of these walking on their hind legs, run. It wants to hug you, and if you put two and two together, you'll realize it isn't a friendly hug (the biggest anteaters kill predators that way).
Poison ivy is gorgeous. It has glossy green leaves which are red when new, and a stunning purple fall color. It also has attractive white berries that birds love. It causes ferocious allergic reactions. Once it's on the skin, most efforts to alleviate the pain will only serve to spread the irritant oils. It grows quickly, and with its berries so appealing to birds, spreads rapidly. If burned, its irritants will be carried in the smoke, and will tear up the lungs of anyone who inhales that smoke. It also seems to be responding to elevating atmospheric carbon dioxide levels by increasing the potency of its irritants.
On the other hand, half of the population likely to be exposed to it is just flat out immune. Amusingly, when the MythBusters attempted to test poison ivy home remedies, none of them proved to be susceptible, though admittedly it could conceivably have been a false negative, as it's possible they had never been exposed to it before; like all allergic responses, the initial exposure does not produce an effect but every exposure thereafter does.
Skunks. They're cute, gentle, and will totally ruin your day if you even make a wrong move around them.
A lot of plants look totally harmless but are actually quite dangerous. For instance, Oleander has beautiful flowers but it is very toxic.
Special mention should go to teddy bear cholla, a cactus which, despite the name, is phenomenally un-cuddly. The name comes from the fact that it looks almost fuzzy, which, combined with the strange shapes it tends to grow in, makes it look kind of comical. The "fuzz," however, is actually thousands upon thousands of hair-thin, transparent, barbed thorns that come out at the slightest touch and lodge in your skin. Guess bears are REALLY bad news.
Honourable mention must go to the giant stinging tree. It does the same while looking EVEN more unassuming. One slight breeze and everything in a 3 block radius suddenly feels like it's ON FIRE!
Grasshopper mice are tiny, fuzzy, and cute. They also howl like wolves and supplement their usual diet of insects with the occasional snake.
Inverted with the Hickory Horned Devil caterpillar, the largest caterpillar in North America and larval form of the regal or royal walnut moth. It's five inches long, covered in menacing-looking spines from head to end, and yet it's completely and totally harmless.
Show breeds of Cocker Spaniel are subject to a phenomenon known as "Cocker Spaniel Rage," in which they flip out and attack for no apparent reason. That's right, Lady may one day try to kill you out of the blue.
Chihuahuas have a lot of bad temper and use to attack in packs, like a horde of angry rats. Some people have been savagely mauled by packs of the tiny bastards, including a police officer in a 2005 incident. Makes one wonder why Paris Hilton is fond of them...
Swans: graceful, regal, a symbol of love ... and equipped with wings strong enough to break your arm at a blow if you come near their eggs.
Velvet worms. Probably another Ugly Cute example, but they're soft and squishy things that crawl slowly over the forest floor on stubby legs. And are predators. That can kill prey the size of tarantulas. (They do it by spraying a sticky slime that quickly hardens into a net to trap their prey. And then they close in and eat the helpless prey alive.)
Moles. That's right, the blinky/blind, fuzzy, shy-but-friendly little guys. These guys may be cute, but they are vicious little blighters: they are predators capable of hunting underground, and burrowing their own tunnels to do so, and are incredibly territorial. Oh, and cannibalistic- put two moles together for any length of time and you end up with one fat mole.
Do not go to pet a dingo. They might look like Labrador Retrievers, but they're very much not domesticated, so for the love of god and for the love of your future children, do NOT pet it!
Tasmanian devils. They're actually much cuter in real life◊ than the cartoon character, but they are obligate carnivores with the strongest bite of any mammal, able to take down prey as large as a kangaroo. Not to mention they're extremely tempermental and loud.
Inverted with the Horseshoe Crab. They have dangerous-looking spikes on their tails and bodies and tails that look like stingray tails, but they're harmless and can't really hurt you.
The mantis shrimp is a small, often colorful little critter that lives in coral dens and mostly keeps to itself. To eat its dinner of molluscs and crustaceans though, the mantis shrimp doesn't bother with prying them open: it BLASTS them open with its clublike arms, which strike with the acceleration of a .22 BULLET. The force generated per area is so powerful that the mantis shrimp can COMPLETELY MISS it's target and STILL do damage by force alone. Captive mantis shrimp have been known to crack or shatter aquarium glass with a single blow. They have another name: thumbsplitters.
An awful lot of tropical reef fishes and invertebrates, including the drop-dead gorgeous ones popular for saltwater aquaria, are deadly poisonous, and even the nonvenomous species may sport razor-sharp spines for protection. Heck, even the coral can cut you to ribbons if the current makes you bump into it.
Shrikes are small, cute songbirds that kill mice and lizards by impaling them on thorns, then use the neatly strung-up corpses as a larder.
Most large frogs, but special mention goes to the American Bullfrog. Funny-looking, not particularly fast, no obviously deadly attributes. But it will eat anything. ANYTHING. In Southwestern areas, it will jump out of the water at night to hunt lizards, rodents, scorpions and tarantulas. If a scorpion is too big to swallow, it will chomp down on it, then fold it in half with its forelegs and shove it down its gullet.
Pretty much anything that isn't newborn and isn't obviously dangerous has potential to be this. Natural Selection is the biological equivalent of Training from Hell on this planet. Even the vegetarians can rip the unwary a new one. Hell, even the vegetables can!
Inverted with Crane flies. They may look like gigantic mosquitoes, but the worst a crane fly can do to someone is when their larvae do some damage to your lawn.
Often rats in many cases. Not only do rats tend to look a lot more aggressive and disease-ridden than their other rodent cousins such as the mouse, they can be more aggressive, and are just as susceptible to carrying and spreading contagious diseases. And can be even worse pests than mice in many cases. Inverted with domesticated rats, which are sweet-tempered and friendly despite their species' bad reputation.
Patterdale terriers and Jagd terriers (German hunting terrier) are still used for boar hunting and vermin hunting. Unlike many dogs, they still have the original strength and ferocity since they did not become just show dogs like dachshunds.
The more brightly-colored and striking an amphibian is, the more poisonous its skin is likely to be. This also applies to insects, fish and reptiles. Its theorized that these bright, striking colors act as a warning for predators that says "do not eat me, I'm poisonous". Some species, such as the king snake, go so far as to imitate this look despite not being poisonous themselves.
The Hippopotamus species have a popular reputation of being fat and contented creatures. However, they are highly territorial and kill more people in Africa than lions. Including killing lions. And despite their huge size they can outrun humans. To put this in perspective, Steve Irwin, the Crocodile Hunter, described a short boat-ride over hippo-occupied water as the scariest moment of his life. Steve Irwin.
When people think of seals and other pinipeds, they tend to visualize the cute, adorable circus or aquarium animals that have been trained to honk horns or bounding happily on the beach. People even consider them to be the sea's equivilant of a dog. However, sea lions are immensely aggressive and have been known to seriously maul humans, in addition to routinely killing each other. Antarctic expeditions have been attacked and at least three people have been killed by leopard seals in the past. Oh, and those goofy-looking elephant seals? You know, the big ones with the silly, drooping noses? Here's a video of one having a disagreement with a parking lot...looking strangely adorable while doing so.
The pelican, a waddly goofy looking bird with a weird neck and beak pouch, the larger ones can eat a pigeon in one swallow.
The very birdlike flying dinosaur Microraptor from Cretaceous China. It looks like an arboreal, four-winged chicken with teeth, and probably (most of the time) behaved as such. However, it belongs to the Dromaeosauridae family. In other words the raptor family!. So this cute little birdie wannabe shares a close family relationship with such monsters as Velociraptor, Utahraptor, and Deinonychus!
A Belorussian man was attacked and killed by a Beaver, similar, non fatal attacks have occured in other places.
If you think snakes are cute at all, baby venomous snakes fall under this, especially baby cobras. They have huge eyes and a cute stripey pattern. They're no less venomous than adult snakes, and sometimes even inject more venom than an adult snake would, because they haven't learned how to use it yet.
One of the biggest warnings that anyone will receive when doing amateur diving on or near tropical coral reefs is "don't touch the fire coral". Fire coral isn't a true species of coral, its actually more closely related to jellyfish and anemones. This is what one variety looks like◊. Like jellyfish, they have nematocysts, which shoot out and deliver venom into anything that touches the fire coral. If you so much as brush one with your bare skin, you will be in some of the worst pain of your life.
Subversion: Siberian musk deer. Seen from afar, it's an adorable bambi. Seen from up close, it's an adorable bambi with creepy vampire fangs. Despite the look, it's not a particularly dangerous animal.
Humans. We are much cuter (from a human point of view, at least) and weaker than many animals, and yet we can eat things that are not supposed to be eaten by anything (spicy foods are supposed to be repulsive to mammals, potatoes, almonds and many other foods are poisonous and yet we found a way to make them edible, and blowfish is supposed to be an insta-kill), and have eaten to extinction many animals bigger than us that were unlucky enough to first meet humans after we had perfected our hunting techniques (big animals that are still around were either lucky enough to see us perfecting our techniques and learned to fear us or lucky enough to live near better preys and have time to learn to fear us while we exterminated something else). Everything's fearsome on this world, including bears, sharks, tigers, crocodile, and pretty much anything on this list, fear starving humans, because, with modern hunting techniques and weapons, the only reason they're still alive is that we learned restraint.
Armadillos; generally they'll flee from any humans by burrowing, and prefer to lock themselves in place if you try to root them from a surface it take effort to dig through, but most Armadillos carry leprosy, which they're immune to. A single swipe on raw skin could very easily give you one of the most feared contagious diseases in world history.
The porcupine puffer is a friendly-looking curious fish that also happens to be a vicious predator. Yes, you read that right. Porcupine puffers (like all puffer fish) have teeth are formed into a beak-like shape that's razor sharp. Likewise, they have powerful jaws that allow them to crack open the shells of creatures like clams and snails. Here's one eating a hermit crab.
They're not short on defenses either. Like all puffers, they can inflate their bodies to intimidate predators, and they have the added bonus of being covered in sharp pointy spines (hence how they got their name). And, if those defenses don't work...Well, did we mention that their bodies contain a poison that's 1200 times deadlier than cyanide?
Puffer Fish are also notoriously territorial, even the little ones, to the point where they'll attack any other fish in the same tank. Now, that may not seem like much, until you realize that they are known to attack fish much larger than themselves. There are many accounts of fish owners putting a larger fish in the same tank as the puffers only to check on the tank the next day and find the larger fish is dead. Turns out the larger fish died a slow agonizing death because the puffers would repeatedly attack and tear it to shreds.