Beelzebub appears in the novel. As Mal, Evie, Carlos and Jay are heading to Nowhere to find the Forbidden Fortress, Jay spies a shadow moving towards them scaring the group. But after it steps out from the shadows and is revealed as Carlos's cat which he got when he was little. He tells her to return home to Hell Hall.
- She is the only one of the main four's sidekicks to appear. Evie and Jay mention theirs, but they are never seen.
- Beelzebub came from 'baddie' bags given out at Evie's sixth birthday party.
- She is first mentioned in the prologue of the Isle of the Lost, and appears in Chapter 20, 'Goblin Wharf'.
- Her name is a reference to her father's. Lucifer is the biblical name of the Devil when he was an angel before his fall. Beelzebub is another name for the Devil and one of the seven princes of Hell.