|Latest appearance||"Bad Little Boy"|
The Skeleton Army is Marceline's army of the undead, which she raised from a graveyard in "Henchman." The army consists of twelve undead skeletons with assorted weapons and shields. The chant that Marceline uses to summon them is "Corpses buried in mud that's black, from death I command you to come back!" Although it seemed as if they were going to attack the Duke of Nuts' castle, they were really just going there to party, as a celebration for the first birthday of the Duke of Nuts' second son. They also appear in "Bad Little Boy" when Marshall Lee summons them to fight Fionna.