The Quagga (Equus quagga quagga) was a species of equid that lived in South Africa. It became extinct in the 19th century due to increased hunting of the animal by Dutch settlers. Its name originated from the sound it made, which sounded like "kwa-ha-ha." It is one of the animals that scientists are trying to "breed back" into existence. The Quagga Project, an organization attempting to bring back the animal, are still working on a plan to do so.
Wikipedia has a more detailed and comprehensive article on Quagga