Population: < 100 individuals
Once found throughout southeast Asia, the Javan rhino is now on the brink of extinction, with only a small population left in the Ujung Kulon National Park in Indonesia. Though the species is legally protected, it is still poached for traditional Asian medicine, with its horn rumored to cure everything from impotence to cancer. (It does not.) The rhino is already extinct in Vietnam, and is under severe pressure in Indonesia.
(PHOTOS: A Perilous Danger to Rhinos)