The Black Widow Shark is a cross between a black widow spider and a shark. She attackes anyone who tries to cross the River of Despair. She attacks both the Thunderkittens and Lion-O who barely manage to escape her teeth. A Black Widow Shark appears in the episode Turmagar the Tuska as well; whether it is the same shark or not isn't revealed, but based on Cheetara's comment when they notice her, it's implied that it is the same one.