According to About.com, the photos of a black lion seen on the Internet are fake. The most common picture of a black lion seen online is actually an image of a white lion that has been manipulated by a deviantART.com user.
About.com relates that while the existence of an all-black lion is technically possible, there have been no reports or documentation of any sightings. White lions exist, but they are virtually extinct. George Adamson’s book “My Pride and Joy” reported an almost entirely black lion spotted in Tanzania in 1987, but no real pictures of this animal seem to exist.