The goliath frog is native to the rainforests of Cameroon and Equatorial Guinea in western Africa. This titanic amphibian measures up to 12.5 inches in length and can weigh up to 7.2 pounds. These frogs have actually roamed the Earth for 250 million years - before the dinosaurs! And in case you were wondering, goliath frog tadpoles are no larger than regular ones - they just grow a lot larger and longer than a typical frog!
There really aren't very many goliath frogs anymore. They are now endangered, mostly due to human activity. Since they are so large they make an excellent source of food. It's against the law to hunt goliath frogs, but people still do it anyway. The larger fully-grown adult frogs are the ones that are hunted the most, which has contributed to lower birth rates.
More information on the goliath frog.