Bahamut Sin is the Bahamut summon that is in Final Fantasy VII: Advent Children. In the Final Fantasy games, Bahamut is a dragon summon that is used to fight the enemies. But in Advent Children, this is an evil Bahamut that Cloud has to fight.
He was very, very hard to draw, that he was. But I really like how it turned out. I think that it's one of my best ones.