The rhinoceros beetle, Oryctes rhinoceros, is a kind of scarab, native to various tropical countries, as well as North America. It's main claim to fame is that it is the strongest animal in the world, in relation to its own weight.
The beetle got its name from the horn the males have sprouting from their head. An average specimen is about 150mm long, over 50mm of which is due to this horn. In combination with its incredible strength, the horn can be used to burrow into the dense leaf litter to escape from predators or look for food. Also, it is used by males when fighting off competitors. The two combatants lock their horns and scrabble around for a while, until one of them gains the upper hand and flips the other beetle over in a sort of suplex motion.
Obviously, in terms of raw strength, the big land mammals like elephants are much stronger than the rhinoceros beetle, but when it comes to strength compared to size, the beetle wins easily. Whereas humans can support at most 3 times their own body weight, this beetle can carry around 850 times its weight - that's like me picking up sixty-five cars!
For pictures of the beetle, see: