Don't let the pudgy appearance fool you—the hippopotamus is widely considered the most dangerous large animal in Africa, killing more humans annually than lions, leopards, and crocodiles combined. Its massive jaws open to a terrifying 180-degree angle and generate 1,800 PSI of bite force through foot-long canine teeth. At 4,000 pounds, it can outrun most humans on land and is absurdly agile in water.

The largest land carnivore on Earth, the polar bear is a 1,500-pound Arctic killing machine perfectly engineered for sub-zero survival. Its paw swipe can decapitate a seal in one motion, and it can smell prey from 20 miles away across frozen tundra. Evolution looked at the grizzly bear and said 'what if we made it bigger, meaner, and gave it a fur coat rated to negative 50?'