25 of the Most Dangerous Animals in the World

What makes these animals more likely to cause harm?

top five most dangerous animals illustration

Treehugger / Alex Dos Diaz

A 2019 study at Utah State University examined how many people are injured or killed each year by wildlife in the United States, the first such review to take place since 2002. It found that more than 47,000 people sought medical attention after being attacked or bitten by wildlife each year, resulting in eight fatalities on average.

We used sources from scientific studies, national public health agencies, and the World Health Organization (WHO) to learn more about the most dangerous animals in the world. Since in most cases it is humans who encroach on their habitats and animals merely react or are victims themselves, for the purpose of this list, we're only taking into consideration the number of deaths associated with each creature. Discover what makes these animals so deadly and what leads to their dangerous behavior.

Top 5 Most Dangerous Animals:

  1. Mosquitos
  2. Humans
  3. Snakes
  4. Dogs
  5. Tsetse fly
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Anopheles maculipennis (malaria mosquito)
Paul Starosta / Getty Images

The world’s most dangerous animal is also one of the smallest. But the mosquito’s dangers lie not in its size but in the diseases it carries—mainly malaria, which kills 400,000 people a year and sickens hundreds of millions more. But that’s not all, the tiny insect also carries deadly viruses like dengue fever, yellow fever, Zika, West Nile, and encephalitis. All together, the WHO estimates that vector-borne diseases are responsible for more than 700,000 deaths per year.

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A group of people on a playground
Philippe Beyer / EyeEm / Getty Images

According to the Centers for Disease Control and Prevention (CDC), humans are the second most deadly animals on Earth. Each year, there are an estimated 19,141 homicides, 14,414 of which are attributed to firearms. That means that there are 5.8 homicides per population of 100,000 humans. What’s more, 2018 also saw about 1.2 million emergency department visits due to human-on-human assault.

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Saw Scaled Viper

Saw Scaled Viper in Maharashtra, India
ePhotocorp / Getty Images

According to WHO data, between 4.5 million and 5.4 million people are bitten by snakes each year, of which 1.8 million to 2.7 million develop clinical illness, and 81,000 to 138,000 die. When it comes to snakes, the saw scaled viper is considered the most deadly, causing a higher global snakebite mortality rate than any other species.

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Dog in a field with a stick
Tabitha Roth / Getty Images

Rabies, a zoonotic and viral disease, causes tens of thousands of deaths each year. While rabies is present in all continents (except Antarctica) and can be carried by any mammal, dogs contribute up to 99% of all transmissions to humans. According to the WHO, rabies-related costs are an estimated $8.6 billion per year, and 40% of people affected by rabid animals are children under 15 years old.

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Tsetse Fly

A Tsetse Fly in the dirt
Oxford Scientific / Getty Images

Trypanosomiasis, a disease endemic in 36 sub-Saharan African countries, is caused by parasite transmission by infected tsetse flies. For those who don’t receive immediate treatment, the disease is fatal. Annual cases numbered well above the tens of thousands until 2009, and luckily, sustained control efforts over the last few decades have reduced the number of global cases, with just 977 recorded cases in 2018.

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Assassin Bug

Assassin bug the carries Chagas disease
Ines Carrara / Getty Images

Similar to the tsetse fly, the assassin bug is known for the disease it spreads, Chagas disease. There are between 6 million and 7 million people infected with Chagas disease globally, mostly in urban settings, and the condition accounts for approximately 10,000 deaths per year. Although only about 30% of infected people display symptoms, they are often serious, ranging from strokes to heart attacks.

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Freshwater Snail

A freshwater snail underwater
Qingyue Zhang / Getty Images

When a parasite released by infected freshwater snails penetrates human skin, it can develop a disease called schistosomiasis, causing abdominal pain and gastrointestinal issues. People are mostly infected during agricultural or recreational activities that expose them to dirty water, while communities with inadequate access to hygiene and medical treatment are most at risk. The WHO estimates an annual death rate of 200,000 from snail-derived schistosomiasis throughout the world.

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Ascaris Roundworm

Ascaris Roundworm under a microscope
Dr_Microbe / Getty Images

Out of all the roundworms known for parasitizing in the human gastrointestinal tract, Ascaris lumbricoides is the largest. It causes a disease called ascariasis, one of the most common parasitic infections on Earth, accounting for 60,000 deaths each year.

While there are an estimated 800 million to 1.2 billion people infected with the disease, only about 15% result in symptoms, the sickness typically remains undiagnosed for years until symptoms worsen enough to warrant medical attention.

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Head of a pork tapeworm
"Michael J. Klein, M.D." / Getty Images

Intestinal infection from tapeworms arises from eating undercooked infected pork, poor hygiene, or ingesting contaminated water. They can get exceptionally dangerous when they enter the central nervous system, causing neurological symptoms like epileptic seizures.

In higher-risk communities where the disorder can be more difficult to diagnose (sometimes even written off as witchcraft), the parasites are associated with up to 70% of epilepsy cases. Also known as the “pork tapeworm,” Taenia solium is one of the world’s leading causes of death from foodborne illness.

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Nile Crocodile

A Nile crocodile in Chobe National Park, Botswana
Paul Souders / Getty Images

Although a considerable number of annual crocodile-caused deaths are not reported, recorded, or witnessed, it is estimated that these large semi-aquatic reptiles kill about 1,000 people per year.

The Nile crocodile is likely responsible for most attacks, as it is generally considered more aggressive. Not only is it one of the largest freshwater croc species in Africa (it can weigh upwards of 1,600 pounds), but it is also extremely widespread. In Mozambique, there are over 300 Nile crocodile attacks annually, and in Namibia, there are about 150 on both humans and cattle.

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The Common Hippopotamus

Hippopotamus in Chobe Natiobal Park, Botswana
Winfried Wisniewski / Getty Images

Hippos may seem pretty laid back as they lounge in the water, but these large mammals are actually quite aggressive and are believed to kill between 500 and 3,000 humans per year. In fact, hippopotamus attacks account for the highest percentage of fatalities (86.7%) when compared to lion and leopard attacks. Humans in East Africa tend to live in close proximity to natural hippo habitats, thus increasing the likelihood of human-hippo conflicts.

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Asian Elephant

An Asian elephant in Cambodia
Nick Everett / Getty Images

Even though African elephants are much larger and generally considered more aggressive than Asian elephants, we often see more attacks attributed to the latter due to proximity. African elephants live in larger ranges and vast protected areas (where local communities can steer clear of them), while the smaller Asian elephants are forest dwellers who are more likely to share habitats with people.

Asian elephants are also easier to tame, so they are often used in closer proximity to humans in the tourism industry or the illegal logging industry. In 2019, a newspaper in India reported that the previous year saw 494 people killed by elephants in India.

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A lion in Masai Mara, Kenya
Dale Johnson / Getty Images

It comes as no surprise that these muscular big cats are some of the most dangerous animals in the world. In Tanzania alone, African lions attacked 1,000 people between the years 1994 and 2014. A study in East Africa found that the probability of wild lion attacks increases with proximity to villages and in areas with large proportions of open woodland, bushland, and crops. As humans continue to develop regions closer to protected areas and lion habitats, attacks are bound to increase.

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A howling gray wolf
John Giustina / Getty Images

While wolves in the wild aren’t usually a fatal danger to humans, these large canines have been exhibiting more fearless behavior around humans over the last century. Many of these attacks are linked to rabies, but other emerging patterns of attacks may have more to do with food scarcity or habitat loss. Although not every case occurs in protected areas, national parks in North America typically have guidelines to protect visitors from wolf attacks.

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Great White Shark

A great white shark in Neptune Island, Australia
Image Source / Getty Images

Sharks' reputation as deadly attackers may be exaggerated—you're more likely to die from a fireworks accident than a shark attack—but it isn't completely unwarranted. In 2020, there were 57 unprovoked shark attacks (and 39 provoked attacks) resulting in 13 deaths.

Great whites are responsible for the majority of the fatalities, accounting for over 200 more deaths than the second most deadly, tiger sharks, since 1850. White, tiger and bull sharks are more likely to do damage since they are commonly found in areas where humans enter the water and have more deadly, serrated teeth.

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Australian Box Jellyfish

An Australian box jellyfish in Western Australia
Brett Monroe Garner / Getty Images

Found primarily in the Indo-Pacific and northern Australia, the Australian box jellyfish is known for being the world’s most venomous marine animal. Its tentacles are covered in tiny darts laced with poison, which when injected, can cause paralysis, cardiac arrest, or death almost immediately. This unique species of box jellyfish—which is considered more deadly than common jellies since they swim rather than float—can grow tentacles up to 10 feet long.

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Stonefish in Scorpaenidae, Maldives
Gerard Soury / Getty Images

Thanks to their camouflaged bodies, which have evolved to mimic their muddy, coral-filled habitats, stonefish are able to sit unnoticed at the bottom of the ocean and wait for unsuspecting prey to swim by before attacking. They use 13 defensive spines lined across their back to release venom under pressure, resulting in pain, swelling, or necrosis. While there have been few human deaths attributed to stonefish, a sting will still require immediate medical attention.

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Deathstalker Scorpion

Deathstalker scorpion in the desert in Israel
Lastovetskiy / Getty Images

The world’s most venomous scorpion only grows to about 11 centimeters in length, but its lethal stinger packs a powerful punch—a study published in Functional Ecology measured the deathstalker’s stinger snapping over its head as fast as 127.9 centimeters per second. Between 2005 and 2015, the U.S. Poison Control Center sent 16,275 people to healthcare facilities due to scorpion stings, more than half of which occurred in the state of Arizona.

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Honey Bees

A honey bee on a flower in California
Sumiko Scott / Getty Images

From 2000 to 2017, there were a total of 1,109 deaths from hornet, wasp, and bee stings in the United States (an annual average of 62 deaths), according to CDC statistics; about 80% of deaths were among males. Anyone with an allergy can die from a bee sting, but since honeybees are considered the most abundant and widespread, you’re more likely to be stung by one of them.

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Golden Poison Frog

A golden poison frog on a tree branch
Sergio Amiti / Getty Images

The largest of the poison frog species doesn't grow more than 2.3 inches in length, but its skin secretes a poison called batrachotoxin that can cause paralysis and death—even in small amounts.

Scientists believe that these endangered frogs, endemic to the Pacific coast of Colombia, sequester lethal amounts of batrachotoxin through their diet of poisonous ants. They are able to avoid poisoning themselves thanks to a naturally occurring substitution at the batrachotoxin receptor within their muscles.

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Brown Bear

A European brown bear in Bavaria, Germany
Raimund Linke / Getty Images

Brown or grizzly bears are believed to be more aggressive than other types of bears, such as black bears, but they also happen to be the most widespread bear species globally. Research on bear attacks in Alaska between 2000 and 2016 found that a total of 96% of attacks involved brown bears, and the number of conflicts is rising. Scientists consider factors like growing human populations, development into bear habitats, and expanded brown bear ranges due to global warming as possible contributing factors.

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A stalking lion
Ben Denison / Getty Images

While wild tigers are found in different parts of Asia, the country of India holds about 70% of them. Tiger attacks on humans are relatively rare, with between 40 and 50 fatalities each year, and are predominantly attributed to conflicts involving livestock as agricultural lands continue to overlap with wild animal habitats. Occasionally, but certainly not always, the number of humans killed is connected to a single predatory tiger.

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A deer buck running
Chase Swift / Getty Images

One would think that these innocent-looking herbivores would be anything but dangerous, but in reality, deer are connected to more deaths in the United States every year than pretty much all other animals combined. Over 58,000 people are implicated in a deer-involved vehicle collision each year, with about 440 people killed annually.

Including them in this list of dangerous animals may be controversial, as deer are themselves the victims of the interaction, but the selection is based on mortality numbers alone.

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Sydney Funnel Web Spider

Sydney funnel web spider in Australia
Photography by Mangiwau / Getty Images

Found in Australia only within a 100-mile radius of Sydney, the Sydney funnel web spider is packed with venom made up of complex toxic proteins that overload the body's nervous system and can kill within 15 minutes.

Male Sydney funnel web spiders are particularly dangerous, tending to hang out in small burrows or crevices in colonies of up to 100. According to the University of Melbourne, this particular spider is believed to have been responsible for 13 deaths before the development of antivenom in the 1980s.

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African Buffalo

African cape buffalo in Tanzania, East Africa
TorriPhoto / Getty Images

The only species of wild cow found in Africa, the African buffalo is characterized by its heavy ridged horns used to fight against predators or for dominance against other males. These horns, combined with their natural aggressive nature and massive size, make them exceptionally dangerous. In East Africa, they are known for breaking down fences in order to raid cultivated crops, which sometimes results in human conflict and deadly accidents.

What Makes an Animal Dangerous?

As you can see, animals deemed dangerous aren't always equipped with scary claws and fangs. Some are slow creepers, going virtually unnoticed when they initially attack. Here are some ways animals can be dangerous.

  • Sheer size, like with elephants, grizzlies, and hippos
  • Speed, a benefit of big cats
  • Teeth, hence the danger of sharks
  • Venom and diseases, because it's not always the bite but, rather, what's in the bite
  • Overpopulation causing car collisions
  • Tool using, uniquely the case with humans
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