There is an opposite of albino animals, which aren't white, but black. These are known as Melanistic animals.
Melanism, which is also hereditary and is produced by the mutation of different genes, results in an excess of dark pigmentation in an animal.
Melanism is found in many different species, including amphibians, reptiles, and mammals. The "Black Jaguar" was once thought to be a separate species but is now known to be a melanistic version of the same species.