Frank and Louie is the name of a cat with one head, two faces, and three eyes. Their mutation is called diprosopia or craniofacial duplication—a very rare type of mutation that causes an animal or human being to have two faces on one head. Cats affected with this mutation are also called “Janus cats” The cats have one brain, and their middle eye—which is also their biggest eye—does not function. They eat with Frank’s face, since Louie’s face does not have a lower jaw and is not connected to their esophagus.