MontanaHatchet on 13 September 2007
Sonic Adventure 2 Battle. Most fans consider it a Black Sheep, even if it was a good game.
I can't really come up with another answers, as there are several series with many different black sheep, due to a general decline in the quality of the games (Spyro, for example).
Tomb Raider: The Angel of Darkness is widely considered the series' black sheep, so I'm going with that. If not a black sheep, at least a bad game.
