Skeleton Princess (also known as Zombie Princess) is the ruler of the Boneyard Kingdom and first appears in the Ice King's Imagination Zone in "What is Life?." She later appears in "Loyalty to the King" as one of the princesses who is interested in the Nice King (Ice King's alter ego). She does not say much and seems to like biting things, as seen in "Loyalty to the King," when she repeatedly bit the metal bars of the cage she was in. She is also seen with Purple Princess and Hot Dog Princess walking in a circle with Nice King.
She appears again in the episode "Princess Monster Wife," where she is one of the princesses that Ice King likes a particular body part of as he steals her left leg.
Skeleton Princess makes another brief appearance in "Princess Potluck," in which Finn either does not recognize or does not remember her and refers to her by "heyyyy, youuu." In "Princess Day," she is considered to be a registered princess.
Skeleton Princess appears to be a skeleton wearing a battered dress with a lavender bodice and a grey-brown frayed or feathery-looking skirt and collar, as well as a pair of tall, dark slate gray boots. The color of her boots is the same color as her medium-length hair. She wears a small, gem-less three-pointed crown. She limps when she walks.
- "What is Life?" (no lines)
- "Loyalty to the King" (no lines)
- "Princess Monster Wife"
- "Princess Potluck" (no lines)
- "Princess Day" (no lines)
(Grumbles) This happens sometimes.
- According to character designer Natasha Allegri, Skeleton Princess' skirt is made out of dead birds.
- She is one out of the two princesses who are skeletons. The other is Princess Beautiful.
- She is Pendleton Ward's favorite princess.
- Skeleton Princess is shown on "Loyalty to the King"'s title card chewing on the Ice King's arm.
- In "Princess Monster Wife," her leg was stolen, but she states that her leg disappears sometimes.
- It is shown that she has two beds: one is a regular bed made of skulls, bones and animal fur, and the other is similar to a coffin with a big orange jewel, placed as a gravestone with a tiara crown inside.
- In "Princess Potluck," she is seen sitting at a table, talking to Princess Princess Princess and Embryo Princess.