Survival Animal Attacks

What Is the Deadliest Animal in the World?

Some of the world’s most dangerous critters are in your own backyard
Katie Hill Avatar
white-tailed deer running in front of car
Some of these deadly species might surprise you. Carol Hamilton / Adobe Stock

What is the deadliest animal in the world? If your mind immediately went to powerful predators like grizzly bears and lions, I hate to disappoint you. In reality, the deadliest animal in the world is also one of the most abundant. 

It’s hard to put an exact number on how many humans are killed by animals every year. That’s  partly because, in rural or remote areas with warmer climates and limited access to healthcare, quantifying deaths is quite difficult. If we take this question to mean what species kills the most humans globally every year, there’s only one clear answer. But for the sake of education (and the shock factor of how many fatalities some of these species cause), we’ll also look at the deadliest animal in the U.S., as well as the deadliest mammals and reptiles on the planet, too. Finally, we’ll round out our search with a list of not-so-honorable mentions. These exotic species might not rack up human death tolls, but they do pose a deadly risk to anyone daring — or stupid — enough to venture onto their turf. 

What Is the Deadliest Animal in the World?

Mosquitoes Are the Deadliest Animal in the World

mosquitos swarming hand
Moquitos can be extremely annoying…and quite deadly.

All Canada Photos / Adobe Stock

Mosquitoes are the deadliest animal in the world to humans by a large margin. This is because mosquitoes transmit malaria, which killed between 625,000 and 627,000 people in 2020, per data from the CDC and WHO. That figure was down from an estimated 780,000 fatalities in 2016. It dropped even more to 619,000 fatalities in 2021. Approximately half of the global population lives at risk of malaria. Large carnivores like tigers or crocodiles couldn’t keep up with that pace if they tried.

These figures don’t account for other sometimes-fatal mosquito-borne diseases, either. Dengue fever accounted for another 4,000 deaths in 2023, according to the ECDC. West Nile virus is another significant concern, even in the United States, where 2,776 people died from West Nile between 1999 and 2022. 

Unfortunately, humans (yes, biologically speaking, we’re animals) also kill hundreds of thousands of our own every year, whether on purpose or by accident. But reliable data on how deadly humans are is nearly impossible to track down, and anyone would be hard-pressed to argue that any of these animals are more capable of mass destruction than we are. Other runner-ups for the title of deadliest animal in the world include:

  • Snakes kill 81,410 to 137,880 humans annually (WHO, 2023)
  • Dogs kill 25,000 to 30,000 humans annually (Statista, 2022)
  • Sandflies kill 24,200 humans annually (due to parasites that cause leishmaniasis, Global Burden of Disease Study, 2015)
  • Freshwater snails kill 10,000 humans annually (due to burrowing parasitic larvae causing schistosomiasis, STAT, 2016)

Deer Are the Deadliest Animal in the U.S.

deer running through road
Deer kill more Americans every year than any other animal.

mtatman / Adobe Stock

Before you reach for one of the best bear defense handguns, consider that the deadliest animal in the U.S. is actually an herbivorous game species. With the overwhelming prevalence of whitetail deer in urban and suburban parts of the country, deer-vehicle collisions and deer-caused accidents account for more than 400 human deaths a year, according to zoologist Dr. Michael Conover. In 2022 alone, insurance company AllState processed 1,378,542 deer-related auto claims.

Mosquito-borne malaria doesn’t pose nearly the same problem in the U.S. as it does in more tropical climates. But West Nile virus is becoming much more of a concern as climate change warms southern states, encouraging more mosquito breeding and survival. The first U.S.-born cases of malaria in 20 years showed up in Texas and Florida in July 2023. But in 2022, 93 people died from West Nile virus. In 2021, that number was 227. Human fatalities caused by large predator attacks don’t hold a candle to this disease or other types of animal fatalities in the U.S. Here are some other runners-up to deer for deadliest animals in the U.S.:

  • Mosquitoes kill 120 humans annually (due to West Nile virus, CDC, 2023)
  • Bees, wasps, and hornets kill 60 humans annually (due to anaphylaxis from stings, Elsevier, 2018) 
  • Dogs kill 30 to 50 humans annually (due to bites, National Institute of Medicine, 2022)
  • Poisonous snakes kill up to 5 humans annually (CDC, 2021)
  • Bears kill up to 5 humans annually (all species included, multiple sources, 2023)
  • Poisonous spiders kill up to 3 humans annually (Cleveland Clinic, 2021)

Dogs Are the Deadliest Mammal in the World

stray dogs running through street
Dogs kill the most humans of any mammal in the world, either through attacks or disease spread.

NurPhoto / Getty Images

As noted above, dogs kill more humans globally than any other mammal. But that doesn’t mean some large mammals don’t require an extra dose of caution, so you should brush up on how to survive a predator attack. Many large African mammals have also more than earned their reputation as “dangerous game,” and make up our entire list of runners-up for the deadliest mammals in the world:

  • Elephants kill 500 humans annually (Britannica, 2014)
  • Hippos kill 500 humans annually (Britannica, 2014)
  • Lions kill 250 humans annually (USA Today, 2019)
  • Cape buffalo 200 humans annually (USA Today, 2019)

Saw-Scaled Vipers Are the Deadliest Reptile in the World

saw-scaled viper on a stick
Saw-scaled vipers are small and elusive, which is why they’re such effective killers.

Arun Sankar / Getty Images

As OL contributor Tim MacWelch pointed out in his story about the most dangerous snakes in the U.S., very few people die from the thousands of venomous snakebites that occur each year in North America. But on a global scale, the fatality rates are much higher, especially in places with limited access to healthcare — and far more dangerous snakes.

While it’s nearly impossible to get exact numbers on death rates from snake bites, saw-scaled vipers are thought to kill more people every year than all other snake species combined. They are part of what zoologists refer to as the Big Four of India’s venomous snakes, which are responsible for the overwhelming majority of snakebite deaths on the subcontinent. Here are some other deadly reptiles: 

  • Indian Spectacled cobras, Indian Common kraits, and Indian Russell’s vipers (the other three of the Big Four) kill tens of thousands of humans annually in India alone (PLoS Neglected Tropical Diseases, 2022)
  • Crocodiles kill 1,000 humans annually (Statista, 2022)

Other Deadly, Poisonous, and Dangerous Animals

box jellyfish in south africa
Untreated box jellyfish stings kill dozens of humans every year.

Enrico / Adobe Stock

There are a lot of deadly species out there that humans rarely, if ever, interact with. In fact, some of the most venomous snakes and poisonous amphibians have never killed a single human because they live in places completely void of civilization. Other deadly species, like the marine creatures on this list, are only deadly because they happen to live and hunt near coastal areas where humans surf and swim. So consider this a list of honorable mentions for the deadliest animals in the world.

Deadliest Animal FAQs

What is the most dangerous bird?

The cassowary, a descendent of the velociraptor, is widely considered the most dangerous bird in the world. Similar to the emu and the ostrich, cassowaries can grow up to 6 feet tall and jump-kick perceived threats with their lethally sharp, 4-inch claws. Cassowaries live in Australia, New Guinea, and the surrounding islands and can run up to 31 mph. They are also fantastic swimmers.

What mammal kills the most humans in a year?

After humans, dogs are the deadliest mammal in the world. Dogs kill roughly 25,000 to 30,000 humans annually either through fatal attacks or transmitted diseases like rabies.

What country has the most mosquitoes?

The country with the highest mosquito population is Brazil, followed by Indonesia, Australia, and the Philippines. While you might assume that the highest concentrations of mosquitoes are in the Brazilian Amazon, mosquitoes are actually quite problematic in Brazilian cities, the CDC notes.  

Final Thoughts on the Deadliest Animal in the World

deadliest animal in the world
All buzz, all bite.

Alexis Bonogofsky / USFWS

It might be shocking that some of the most deadly animals in the world are small insects you could crush with a slap. But insect-borne diseases continue to be a major health risk for much of the global population. Beyond the scary realm of insects and parasites, large predators like wolves, grizzly bears, lions, and tigers all give way to dogs and other humans as some of the deadliest mammals in the world, too. We’re not kidding when we say some of the deadliest creatures on the planet are probably in your own backyard.