Greater One-horned Rhinoceros
Rhinoceros in Riyadh zoo
Two close encounters with One-horned (Indian) Rhinos during a jeep tour of Chitwan National Park in southern Nepal: the first sighting was a large male who lumbered out of the forest to take a swim in a pool within feet of the trail; the second was an immature female lacking a horn.
Rhinos, sadly poaching is rife and extremely difficult to control at present, with a magnitude of increase in killing since 2005. Cannot now tell if these were black or white, photos are cryptic, memory faded...so going with the former (thanks Laorie for comms).