I found this in 2 seconds using google. When I get a chance I will find you a better article.

8. Can cougars be black?
There is no scientific documentation that a black color phase exists in cougars in North America. Several species of the larger spotted cats (leopard and jaguars) do have black color phases. An exotic cat called a jaguarundi, which looks somewhat similar to a cougar -- just a smaller size, has a black phase.