Yes there are, it's a rare pigmentation disorder, I believe there are only 1 or 2 alive today, both are in containment, it's really rare( albinism is FAR more common) but it has happened, most die in the wild, because they stand out, and if found by poachers, would be obvious and rare prey.
There in nothing like black lion. There has never been and there isn't a lion with a black color. All lions are always yellow in color, but dark than yellow. You can never find a lion with a different color.