The Peanut Baby first appears in the episode "Henchman." He is the second son of the Duke and Duchess of Nuts, the first being Marquis of Nuts. In the episode, Finn is terribly scared that Marceline will try to kill or eat him. It turns out that she is scheduled to play for his birthday party, and she plays the "Fisherman Song" for him on her ax bass.
- Despite being the son of the Duke and Duchess of Nuts, he is technically a legume, not a nut.
- He appears in Adventure Time: Hey Ice King! Why'd you steal our garbage?!! when the player needs to find him in order to continue the game. He ends up being in Lemongrab's dungeon.