Megalodon (Carcharocles megalodon) This ancient shark was far larger than any modern-day predator, with estimates suggesting it could reach lengths of up to 60 feet.
Titanoboa (Titanoboa cerrejonensis) The Titanoboa was a giant snake that lived around 60 million years ago and could grow up to 42 feet long.
Therizinosaurus This dinosaur may not have been the scariest in terms of size, but its enormous claws—up to 3 feet long—could definitely intimidate anyone.
Short-faced Bear (Arctodus simus) Weighing over 3,500 pounds, the short-faced bear, which roamed North America during the Pleistocene era, was one of the largest carnivores ever.
Giant Ground Sloth (Megatherium) These massive sloths, weighing as much as 4 tons and standing over 20 feet tall on their hind legs, were not only terrifying because of their size but also because of their huge, powerful claws.
The Saber-toothed Cat (Smilodon) With its trademark elongated canines that could exceed 7 inches, the saber-toothed cat was an apex predator of the Ice Age.
Chimera (Prehistoric "Ghost Fish") Often considered a "living fossil," the chimera fish (also known as the "ghost fish") evolved in a time when monstrous sea creatures like the giant shark and massive squid roamed the oceans.