The 7 Scariest Animals in the World

Nov 01, 2023

An Irukandji Jellyfish

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Animals have long been a source of fascination and fear. France’s Chauvet Cave is adorned with paintings of hyenas, lions and bears, making these depictions some of the oldest — if not the oldest — drawings in the world. Whether for their looks, deadly nature or sheer size, every creature on this list earns a top spot as one of the scariest animals in the world. Prepare to feel uncomfortable. 

1. Colossal Squid

The title of the world’s largest invertebrate — and, perhaps, the most spine-chilling animal in existence — goes to the colossal squid. Weighing in at a whopping 1,100 pounds, it’s even bigger than the giant squid!

It wasn’t enough for this deep-sea behemoth to have suction cups on its tentacles like a normal squid or octopus. Its appendages also have hooks on them for grabbing prey and, perhaps, to fight back against its main predator, the sperm whale. Researchers have discovered sperm whales with colossal squid beaks in their stomachs as well as scars of unknown origin on their backs. 

With these animals living at depths of over 3,200 feet, it’s unlikely you’ll ever encounter a colossal squid as you enjoy some time out on the waves. If you do, however, consider yourself lucky to see one. Only a handful of specimens have ever been recorded.

2. Fish Tapeworm

Sushi lovers, take note — one of the scariest animals in the world is a lot smaller than a colossal squid, and it could be hiding in your California roll. Diphyllobothrium latum, the fish tapeworm, gets into your body when you eat raw or undercooked fish that contains tapeworm cysts. The cysts hatch into adult tapeworms in your small intestine, where they specialize in absorbing your vitamin B12. 

You’ll develop a disease called diphyllobothriasis. In addition to experiencing muscle weakness, dizziness and weight loss, you might have one of the scariest side effects of vitamin B12 deficiency — psychosis. Patients severely lacking B12 can suffer hallucinations, suspiciousness, disorganized thinking and delusions, including persecutory delusions where you think someone’s out to get you. 

And, in a way, someone is out to get you. They just happen to be a tapeworm. 

3. Sloth Bear

Despite its cuddly appearance, the shaggy, black-and-white sloth bear is one of the scariest animals in the world and has earned a reputation as the most aggressive type of bear. In terms of absolute numbers, this is the bear species that most frequently attacks humans. It tends to maul victims’ faces in response to being startled. 

No one is sure why this Indian bear behaves so defensively when encountered. However, some scientists think the animal developed this behavior as a response to co-evolving with tigers, which prey on it when they have the chance. As human development encroaches more and more on the sloth bear’s territory, attacks will likely become more common. 

4. Irukandji Jellyfish

Not many animals get the honor of having an entire syndrome named after them. The delicate brush of the Irukandji jellyfish’s tentacles — or even its bell, which, unlike most jellyfish, also possesses stingers — can induce instant agony. The venom causes Irujandji syndrome, an illness characterized by severe muscle cramps, vomiting, headaches, kidney pain and, most disturbingly, a sense that something horrible is about to happen. 

Many victims die of cardiac arrest. Among survivors, symptoms can linger for up to two weeks. 

Thankfully, Irukandji jellyfish only live in the northern marine waters of Australia, making it much easier to avoid them. 

5. Aye-Aye

Although not dangerous to humans, the aye-aye is one of the scariest animals in the world for its appearance alone. As if it wasn’t enough to look like a possum with mange, this bizarre primate also has hands that look like tangled masses of spiders. It uses its long, spindly middle finger to dig for bugs inside of tree bark, and its yellow-green eyes bulge in a perpetual state of surprise. 

Some Madagascar natives believe the aye-aye is a harbinger of death and that it uses its middle finger to stab sleeping people in the heart. Unfortunately, superstitions like these are one of the reasons the aye-aye’s population is declining. Habitat loss and degradation also play a huge role in the loss of many species in Madagascar.  

6. Spotted Hyena

Few sounds evoke such visceral fear as the whooping laughter of the spotted hyena. Being from Africa, the carnivore is likely one of humankind’s oldest predators, which may explain why so many people from different backgrounds dislike it.

In addition to its infamous laugh, the spotted hyena makes a hair-raising repertoire of noises, including a guttural growl that sounds like a chainsaw cutting brush, a violent choking sound, and a woman — but with something just a little off about her voice — crying out in the darkness. They can also digest bones. 

If you need more convincing that spotted hyenas are one of the scariest animals in the world, the scavengers are born with full sets of teeth that help them fight their siblings for dominance, sometimes to the death. Yikes. 

7. Cassowary

The cassowary is living proof that birds evolved from dinosaurs. Sporting three dagger-like claws on each foot, it’s one of the few birds capable of killing a human. This emu-like species can run up to 30 miles per hour and leap five feet in the air.  

Thankfully, cassowaries are elusive and prefer not to get involved with humans. Attacks are rare and typically happen when people give the birds food. Of all reported attacks, there have only been two deaths associated with cassowaries — one when two teenage boys attacked a cassowary with clubs, and another when a cassowary breeder tripped and fell in the animal’s enclosure. 

Still, the mere fact that a bird can be large enough to take down a person is terrifying, earning cassowaries a spot as one of the scariest animals in the world. 

Appreciating Animals From a Distance

As beautiful as nature is, it can also be terrifying. Wildlife encounters are becoming more frequent in many areas because human settlements are pushing out farther and farther, leaving little room for animals to go. 

In most cases, animals want to be left alone — well, except maybe for tapeworms — and you can probably go your whole life without worrying about an animal attack. The world is full of hair-raising beasts, but to them, you’re probably the scariest creature of all. 

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Jack Shaw is a senior writer at Modded. Jack is an avid enthusiast for keeping up with personal health and enjoying nature. He has over five years of experience writing in the men's lifestyle niche, and has written extensively on topics of fitness, exploring the outdoors and men's interests. His writings have been featured in SportsEd TV, Love Inc., and Offroad Xtreme among many more publications.