A 400-pound wall of pure muscle wrapped in a surprisingly gentle soul—until you threaten its family. The silverback gorilla can bench-press an estimated 1,800 pounds and possesses grip strength capable of crushing a crocodile's skull with its bare hands. Pound for pound one of the strongest animals on Earth, and smart enough to learn sign language while doing it.

The undisputed king of the African savanna, the lion commands respect with a bone-crushing bite force and claws that can shred steel-drum lids. Hunting in coordinated prides, a male lion's 550-pound frame and thunderous roar can be heard from five miles away. Few animals dare challenge this apex predator on its home turf.