What colour is a panther?

While black and pink are among the most famous colours, the term "panther" can apply to many cats (including leopards, lions, tigers, and jaguars)and things named after them, with many colour and pattern variations- see https://en.wikipedia.org/wiki/Panther

The sports team Florida Panthers (NHL) is named for a variant of the North American Cougar or Puma, of which https://en.wikipedia.org/wiki/Black_panther says "There are no authenticated cases of truly melanistic cougars (pumas). Melanistic cougars have never been photographed or shot in the wild and none has ever been bred."

Correct. There is no such thing as 'a' panther.

In the United States, 'a' panther, formerly pronounced 'painter,' is a cougar or puma.

Audubon and Bachman illustrate and describe it starting on p. 305 of "The Quadrupeds of North America", published in 1854.

You have to scroll up for the paintings. They are identified as Felis concolor. The modern classification is Puma concolor.
http://tinyurl.com/aenoovf

Us Flahiduh (Florida) Crackers knows there is panthers.
So does the U.S. Fish & Wildlife Service. Here's a whole page on the Florida panther:

http://www.defenders.org/florida-panther/basic-facts

It is a common misconception that Florida panthers are black. They are actually tawny and brown with cream or white colored undersides. Small amounts of black coloring can be found around the face, paws, legs, and tip of tail. Baby panthers are born with black spots that last approximately two months after birth. This is so that their mother can camouflage them better from potential predators.

There is no species of "black panther."

https://en.wikipedia.org/wiki/Panthera