- Wuya's first resurrection. When it begins, we get a brief flash of her human form before a World-Wrecking Wave goes off, causing a solar eclipse and turning the area into a wasteland while the music becomes dark and ominous. Wuya then starts laughing as the camera scrolls up to reveal her human form still wearing her mask...which she takes off to reveal her sharp teeth as she laughs in a pillar of green fire. Wuya goes from a comical sidekick of Jack to a horror show in one scene.
- Omi becoming a demonic and insane Blood Knight after turning evil. To think this is what the little monk boy would be like without his morality but all of his skill."HEYLIN POWER! TSUNAMI WATER BLADE: ICE!"
- The Sapphire Dragon. Just... just the Sapphire Dragon. That thing, along with being an Ensemble Dark Horse of Shen Gong Wu, is considered by many to be one of the scariest things to ever come out of the series. It turns your enemy into solid sapphire with bright blue flames. As well as anyone in remote proximity. And pretty much anyone else it comes across that doesn't subdue it. Worse still, when it's frozen enough victims, they become its slaves.
- Worse is that this dragon has aspirations. It does not stop with just the nearby victims. Without someone to stop it or enough soot to weaken it, it would keep attacking every living thing on the planet until the entire world is turned to sapphire!
- Even the man in the usual Shen Gong Wu demonstration is afraid of it. He sets the dragon's statue form down on the ground and runs like hell away from it as his opponent is petrified. Hell, the scroll even says it's to be used as an absolute last resort since it's the most dangerous Shen Gong Wu to EVER EXIST. Think about that for a second...
- What makes it scarier is just how quiet it is. You'd expect a dragon to be very loud but, The Sapphire Dragon never roars ONCE, except for one time when Dojo accidentally scratches its belly.
- And then there's when the dragon makes a return. Hannibal Roy Bean fuses it with the Shadow of Fear and Moby Morpher Shen Gong Wu to create a freakish hybrid of the Sapphire Dragon and the monster jellyfish that Raimundo is scared of. The Sapphire Jellyfish. Worse still is that this time since it's the manifestation of Raimundo's nightmare, the monster appears whenever Raimundo falls asleep!
- Due to Orifice Invasion with which to control you as a Puppeteer Parasite, Sibini definitely qualifies.
- Dojo's scene with Jack in "Enter The Dragon". Just the way his mouth slowly closes before letting out an evil laugh as he clothes his jaws... yeesh.
- Dojo himself would count as Nightmare Fuel for the episode considering he goes from a goofy comic relief character to an unstoppable and endlessly hungry two-headed monster ushering in an age of darkness that is more than willing to eat his friends and enemies alike, even cracking jokes about how he'll eat his victims. The scenario would have turned into a Bad Guy Winning Scenario if not for Omi managing to seal Dojo back into his containment box to wait out his transformation.
- The giant spiders that tried to devour everyone and everything on Earth.
- The monstrous Chi Creature that escapes from the Ying-Yang World.
- Dojo is given to Chase Young by Master Monk Guan as a gift, and thinks he's going to be fed to Chase's pack of big cats... Only to be given a lavish dinner. For the rest of the episode, Dojo is pampered and treated kindly by Chase, and thanks to all of Chase's food, Dojo noticeably grows fatter and fatter. During a particularly large meal, while Dojo is lounging in a hot tub, this conversation ensues:Chase: Another helping?Dojo: Sure! But I think I'm gonna need a bigger tub!Chase: That can be arranged. It appears you are ready for the Lao Mang Lone soup!Dojo: You're making me a pot of soup?Chase: Yes... In a manner of speaking. (opens a pantry full of soup cans with dragons on them - Dojo finally realized why he's been so well fed)
- The episode The Last Temptation of Raimundo in which numerous Shen Gong Wu come to life with minds of their own, and take over Raimundo's body, gradually mutating it beyond recognition while he pleads for help from anyone nearby.
- It gets worse when he loses all his willpower and Wuya takes over his body, the episode shows he's still conscious but unable to keep control of his Shen Gong Wu infused body
- Hannibal Roy Bean is this for the show considering he's the Greater-Scope Villain responsible for corrupting Chase Young down the path of evil and sealed away in the Ying Yang World by Chase Young who knew he'd be a threat to his rise to power. He even managed to corrupt Master Monk Guan in an alternate verse, showing how corruptive the nasty little bean can be. When meeting Jack in his dimensional prison, he somehow knew much about Jack's personal life despite never leaving his prison, showing he was well aware of the events happening outside his prison. Add the facts he's actually a little bean animated by Heylin Magic that can easily tear through robots and beat down the Xiaolin Monks in his tiny bean form, has a Shen Gong Wu that allows him to shapeshift to take on any form he chooses, and the quality of being a particularly Faux Affably Evil Mastermind, you can see how horrifying he can be. Not to mention he continues to be at large by the end of the show.
- After Omi tampers with history to keep Hannibal Roy Bean from turning Chase Young evil, the Heylin bean decides to go with Plan B and turn Master Monk Guan evil instead. This alternate Guan's monster form resembles a giant mutant crayfish and is deadlier than Chase Young's lizard form.
- While the Monkey Staff is usually played up for comedy, holding it slowly changes you into a monkey, first physically than mentally. And once you hold it for long enough, you don't want to let go of the thing. We've see Jack slowly lose his humanity to this combination of unsettling features twice, the second time to a point Jack appeared to have lost himself near completely.
Nightmare Fuel / Xiaolin Showdown