No source can accurately estimate the number of black panthers in the world because the black panther is not a single species. It is an uncommon color variety that exists in several large cat species. The most common black panthers are leopards or jaguars.
All black panthers receive their coloration from a genetic trait called melanism that causes excess black pigment or melanin. A dominant trait causes melanism in jaguars, and a recessive trait causes it in leopards. Being melanistic may give big cats a hunting advantage in the forest or jungle because black cats are harder to see in dark, dense environments.