The term 'panther' has a confusing history - it's been used to refer to any big, black (i.e. 'melanic') cat, usually the leopard in particular. Leopards and panthers used to be thought of as different species, but they are in fact merely different color variants, and this so-called melanic coat coloration is a recessive Mendelian trait. To complicate matters, the four big cats - leopards, tigers, lions, jaguars - have been grouped in the genus Panthera, based on the same etymological root.
In Southeast Asia, the leopard Panthera pardus exists in two color morphs: the usual spotted variety, and the melanic 'panthers'. However, a recent evaluation of camera-trap data could not find any spotted leopards South of the Isthmus of Kra; all the animals that were photographed by these traps were black leopards. Anecdotal evidence from interviews with aboriginal peoples living in national parks also found that they were unfamiliar with the spotted leopards but could recognize the black ones. Although 'absence of evidence is not evidence of absence', it does show that spotted leopards are at the very least rare in Malaysia. The authors of this study suggest that this trait has become genetically fixed because of a bottleneck event sometime in the history of this population. This is a neat intersection between basic natural history and genetics, having implications for the genetic variability of the Malayan leopards, and hence their conservation viability.