Nightmare Fuel / Land of Oz

The Land of Oz books are children's books classics, but that doesn't mean everything in them is child friendly. Due to a combination of Values Dissonance, Fridge Horror, and intended creepiness, the series contains quite a large amount of nightmarish potential. Scary Oz-related happenings are not left solely to Dystopian Oz reimaginings and Grimmifications.

---

• How Princess Ozma was found in The Marvelous Land of Oz might qualify. She was kidnapped as a baby and sold off to an evil witch who forcibly turned her into a boy. Ozma, raised as "Tip", was treated almost like a slave and mistreated by her guardian Mombi. Eventually, Mombi planned on turning Ozma into a statue, which is why Ozma ran off.
• Princess Ozma had Bungle's brains changed to make her more agreeable. (May count as Canon Discontinuity as Bungle has her old brains and attitude back in later books.)
• Chopfyt was made of the flesh parts of both Nick Chopper (the Tin Woodman) and Captain Fyter glued together with the Wicked Witch of the East's flesh glue, along with a tin arm.
• The Fountain of Oblivion. It is an enchanted fountain that removes all the memories those who drink its Water of Oblivion.
• The Wicked Witch of the West's death is morbid. She melts after coming into contact with water. Dorothy, seeing the the brown puddle that used to be the witch, sweeps it out the door.
• The desert that surrounds Oz. Anyone who touches it turns to sand instantly.
• People cannot die in Oz. We learn this after the Tin Woodman chopped off the heads of various animals and Dorothy accidentally melted the Wicked Witch of the West. The books explain that people in Oz won't die even if they're cut into tiny pieces or exploded. They won't feel any pain, but they'll be conscious nevertheless.
• How the Tin Woodsman got his parts, or rather, how he lost them. He was an ordinary man named Nick Chopper who chopped down trees. He fell in love with a Munchkin girl, something her mother disapproved of. So she made a deal with the Wicked Witch of the East who enchanted his axe in order to prevent him from marrying his sweetheart. The enchanted axe chopped off each of his parts, one by one. Each time he lost a limb, Ku-Klip replaced it with a tin prosthetic until nothing was left of him but tin. Ku-Klip forgot to replace his heart, which is why Nick can't love his former sweetheart anymore.
• When the Tin Woodman meets up with his disembodied head. His former and sentient disembodied head; as he has a tin replacement now.
• The Wheelers, quite possibly one of the scariest things to appear in the Oz books. As pictured above they are humanoid creatures that are described as having long legs and arms of the same length, with wheels for hands and feet made out of BONE MATTER. Not to mention the illustration shows them with menacing red eyes. As if that wasn’t enough they also intend to kill Dorothy because she was hungry and took some of their lunch pails, all while making loud screeching noises at her.
  “Run!” screamed the yellow hen, fluttering away in great flight. “It’s a Wheeler!” “A Wheeler?” exclaimed Dorothy. “What can that be?” “Don’t you remember the warning in the sand: ‘Beware the Wheelers’? Run, I tell you—run!” So Dorothy ran, and the Wheeler gave a sharp, Wild cry and came after her in full chase.
• When the Wicked Witch commands her airborne simian lackeys to destroy the Tin Woodman, and the Scarecrow. She even crosses the Moral Event Horizon by making Dorothy her slave as well as planning to feast on the Cowardly Lion.
• Some of the laws in Oz come off as more scary than intended. For example, their Ban on Magic is so strict that a young boy gets arrested in The Patchwork Girl of Oz for picking a six-leaf clover.
• In Dorothy And The Wizard In Oz, the Mangaboos (humanoid Plant People) are both incredibly beautiful and frighteningly sociopathic. When Dorothy and her friends arrive in their kingdom Beneath the Earth, they immediately blame them for the earthquake that has broken their glass homes (despite their visitors being at least as much victims of this natural disaster) and take further issue with their need to eat (Mangaboos viewing fruits and vegetables as artwork). Their current ruler decides that the heroes must leave immediately but, since there is no way for them to return from whence they came, he orders their execution via Man-Eating Plant, and refuses to consider any less deadly solutions. When the Wizard invokes their Klingon Promotion by awakening the next ruler - a princess - she also decides that killing Dorothy and her friends is the best solution to their problem. As no other members of the Mangaboo species appear as anything other than vain, selfish and greedy, they make for a rare example of Always Chaotic Evil in an L. Frank Baum novel.