Mouthy was a ghost in the form of a mouth. In life, he was a radio personality known as Freddy "The Mouth" Hopkins. After death, he got a gig appearing wherever some ghost feels he should be. He also maintained his radio career but for the ghost community. He visited Mortimer von Fogwhistle under one of his floorboards and explained some of the Ghost Rules to him. (Mark III: "Ghosts!")