Pygmy Hippopotamus
Any one who has seen hippos knows how huge they are, the Pygmy is a much smaller replica of that. Found only in Africa, specifically - Western, the Pygmy Hippopotamus, is nocturnal and herbivorous; unlike the larger, common hippo which is gregarious, the pygmy is very rare, shy and solitary. And endangered.
More on Pygmy Hippopotamus: IUCN, Facts, National Zoological Park, ultimateungulate.com, Wonderclub