The Haunted Castle of Oz is a 2019 novel by Marcus Mebes and illustrated throughout by Kamui Ayami, which follows the continuity of the original Oz series.
There have been strange sightings of a ghost in the palace of the Emerald City, and Ozma wants to get to the bottom of it. She has Dorothy, Betsy, Trot and Button-Bright stay up at night to search the castle, only to find that the "ghost" is the projection of a prince named Terrence from the far-off kingdom of Flora, who requires the assistence of a Princess to usurp the throne from his uncle. The story goes on to include many characters from the Oz books both well-known and obscure.
- Alternate Universe: Flora turns out to be in another universe, separate from both Oz and our own.
- Badass Boast: As he's being defeated Necronimus claims to be "the evil that burns in the hearts of every living creature" among other things, only for Ozma to respond "Oh, do shut up!".
- Evil Uncle: King Gorsbenor is Prince Terrence's evil uncle who stole the throne.
- I Choose to Stay: Part I starts with Terrence, Necronimus and Christian choosing to stay in Oz, although this is undone by the end of the book.
- Multi-Armed and Dangerous: Handy Mandy (from the book Handy Mandy In Oz) uses her seven arms to wield several weapons.
- Multi-Armed Multitasking: In addition to wielding weapons, Mandy is apparently ambidextrous and manages to swiftly copy the layout of the Castle of Flora with pen and paper using all seven arms.
- Necromancer: The wizard Necronimus claims he was forced to be one for Gorsbenor to build his army. It later turns out he wasn't as "forced" as he said he was.
- Night of the Living Mooks: The evil king Gorsbenor commands one, which the party Ozma puts together has to fight. One of their favorite attacks is throwing shards of bone at their opponents.
- Older Than They Look: Everyone in Oz, thanks to their immortality. This comes to the forefront when Terrence proposes marriage to Dorothy in order to help him secure the throne; Dorothy may look ten years old but she's been alive over a century by the time of this story.
- Original Flavour: The book has the look of the original Oz series in terms of the formatting, typeset and illustrations, although the writing itself has a more modern feel.
- Time Skip: There is a two year time skip between Part I and Part II of the book.
- Vile Villain, Saccharine Show: King Gorsbenor, Necronimus and the undead army are a sharp contrast from anyone in Oz, which just illustrates how different Oz is from the Kingdom of Flora.