- Derek Powers nicely sets the Nightmare Fuel tone for the series right from the early going.
- There's also what his deadly biological weapon does. Probably due to censors, we don't actually SEE what happens to a human or an animal, but that arguably makes it worse given what we see it does to plants, and Derek's comment, depending on whether or not you think he was being literal or metaphorical, implies humans hit with it turn to dust if not treated.
- Even the man Derek Powers was selling it to was squicked out when he saw the effects on humans. It's not at all helped by Derek's casual demeanor when showing the effects.
- And of course, there's also Derek Powers' transformation into the supervillain Blight. After getting exposed to the poison gas himself, Derek receives radiation therapy to save his life. The combined effects of the gas and radiation mutate him into what looks like a glowing green skeleton with deadly radiation powers. His new appearance matches his black soul.
- The final fate of Ian Peek in "Sneak Peek". After abusing the intangibility belt, he winds up becoming intangible without it and unable to be selective about what he's intangible to, causing him to fall from the top story of a huge building through floor after floor while Batman's constantly trying to swoop to grab him as Ian's screaming for help. Batman finally manages to grab him and encourages Ian to focus to stay solid, and for a second it looks like it works, until he seems to just lose all spirit and slowly sink into the basement floor, laughing for a moment, then screaming/crying until his voice becomes muffled by the floor and begins his descent into the center of the earth. This guy committed murder, but that is still a horrible way to go.
- Earthmover. Essentially a motionless, decaying corpse half-melted into the surrounding earth — except for the glowing green eyes. Seriously creepy even for this series, especially since his character model was more detailed than anyone else's.
- His VOICE! He sounds like a horrible mix of something demonic and a dying man who can barely even draw enough breath to speak.YOU... LEFT. ME. BURIED!
- It's never made entirely clear what happened to the mind of Tony Maychek upon his transformation into Earthmover. Is he, as suggested in the episode, just an endlessly resounding echo of rage? A last gasp of identity no more conscious than a computer program? Or is he fully conscious, but driven so insane by his situation that no longer cares about anything but vengeance? Or, most chilling of all, is he fully conscious, but no longer able to remember anything of his last life but its final, horrifying moments, endlessly repeated forever in his mind?
- What's worse in terms of Harsher in Hindsight is that Earthmover/Tony Maychek was voiced by Stephen Collins and seeing that the character wants to kidnap his own teenage daughter for himself brings in shudders for viewers in light of Collins' real-life repeated statutory rape crimes.
- His VOICE! He sounds like a horrible mix of something demonic and a dying man who can barely even draw enough breath to speak.
- In "Lost Soul," the final fate of Robert Vance. Whether he was the real deal or just a deluded, rogue program that thought he was Robert Vance, and regardless of the horror he was going to subject his grandson to note (which is Nightmare Fuel in and of itself), seeing (and hearing) the man mentally regress to infancy and cry out for his mother and father as his data is deleted for good is cringe-worthy.Robert Vance: Five hundred megs! A thousand kilobytes! Pi r squared! Two plus two equals four!" (voice then reverts to that of a child, and then becomes baby talk) "Me first! I wanna play! One potato... Two potato... Mama! Papa!... Mama!
- There's also the moment when Vance's program manages to get into the Batsuit. He realizes that Terry is nothing more than a hindrance, so he decides to get rid of him... by drowning Terry. The way that Terry fights the suit as it walks into the ocean is incredibly agonizing to watch. Sure, Bruce realizes what's going on and uses the failsafe "get the suit's joints to lock up" thing, but that only happens once Terry is neck-deep in the water already. He's stuck there, trying to stay upright and alive as he gets hit by wave after wave until Bruce finally comes to get him.
- "Where will I be?" is answered with a deadpan, "Wherever deleted programs go." Robert Vance views his grandson as a program to be erased and replaced with himself.
- Heck, Robert Vance's avatar being a sickly pale face is plenty disturbing in and of itself.
- Just the way the Robert Vance program (or Vance himself, depending on how you look at it) looks on the computer screen with the dead eyes and the ghost-like pallor is Nightmare Fuel by itself. The events of the episode just mix in kerosene with the Nightmare Fuel, and the end where as he's being deleted we hear his memories going back to childhood, ending with the heartbreaking sound of child!Vance asking for his mama just dumps the entire container on and turns it into Nightmare Fuel. There may not be a single episode that can rival how creepy the villain was and how disturbing that end scene was.
- The deaths of the Terrific Trio in "Heroes" are pretty gruesome. 2-D man gets sucked into a ventilation shaft by his torso and shredded by the fan blades, Freon gets her form dissipated by the fans and radiation of the nearby nuclear device, killing her and leaving her remains to be sucked into the air ducts, and Magma gets cooled down by being sprayed with a high pressure fire hose, brutally beaten, and kicked into some equipment before his flames go out for good, leaving a lifeless hunk of rock.
- Terry's mutagenic transformation into a monstrous Man-Bat creature in "Splicers", which is eerily reminiscent of what happened to Kirk and Francine Langstrom from Batman: The Animated Series.Terry: Bruce... Help me!
- Terry arriving back at the Bat Cave with only enough time to toss his mask at Bruce's feet and reveal himself to be almost fully transformed, as he says the above-mentioned line before going full-bat and attacking Bruce.
- Particularly chilling how, after injecting Terry with the splicing serum, Dr. Cuvier calmly tells him, "You're welcome to your opinions, while you're still human enough to have them."
- Dr. Cuvier's final transformation. He starts off injecting various animal DNA into himself to become a chimera. Terry then starts pumping random serums into him, causing him to turn into a... hideously misshapen mass of sinew and bile. See for yourself◊.
- The flashback to Stalker's back surgery in "Bloodsport." It's made very clear that for whatever reason, the surgeons didn't want to put him under anesthesia when replacing his spinal chord.
- The Stalker was supposedly killed when he was run over by a train. Why didn't he leap out of the way? He hallucinated and thought it was a panther. In fact, the Panther that mauled him in the first place.
- The subjugation the kids go through at The Ranch in "The Last Resort." Children are brainwashed Big Brother-style, denied food, sleep, bathroom breaks, or even contact with the outside world until they break. Those that step out of line are put into ISO, which basically amounts to sensory deprivation. Bruce mentions that such tactics are used both in cults and on some prisoners of war, so seeing them used on kids...
- And what makes things even worse is that there are real-life "therapeutic" institutions that do all this and worse to kids, and plenty of sadistic people just like Dr. Wheeler who run them.
- Inque's first serious attempt at killing Batman. She crams herself down his throat! Sure, Bruce and his fire hose come to the rescue, but that's got to be a pretty unsettling way to go...
- How about what she does to Aaron Herbst, that poor guy who helps her get her humanity back in her second appearance? She gives him half the mutagen treatment, leaving him a wretched half-human, half Blob Monster that ends up in the same facility that was studying Inque...
- Everything Inque does. The first time she actually attacks Batman, she does so by blackening the entire screen save for the corner where he is. Talk about Nightmare Fuel for claustrophobiac. And then there is multiples instance of her going full Eldritch Abomination.
- In Return of the Joker, Terry returning to the Batcave to find it vandalized, and Bruce lying on the floor, dosed by Joker venom, barely able to move or speak without succumbing to the venom and nearly laughing himself to death. It had to be a bit of an in-universe example as well, since the scene with the vandalism directly recalls Terry's father's murder.
- Joker's Moral Event Horizon with what he did to Tim Drake. That scene alone speaks for itself and this actually pushes Batman to try and KILL the Joker.
- Also another case of an in-universe example when you retroactively revisit first-season episode "Disappearing Inque." Suddenly Bruce's actual display of very real concern when Inque kidnaps and threatens to kill Terry makes a lot more sense, considering what happened to his last protege when that happened... and explains why he was willing to risk himself in a fight instead of coaching Terry through an escape somehow.
- The feeling was mutual for Terry, when Bruce dons an experimental suit. While us Animated Series fans were cheering that Batman was back, Terry faintly lets out a concerned "No." because he knows that suit is gonna kill Bruce whether he beats Inque or not.
- Joker's Moral Event Horizon with what he did to Tim Drake. That scene alone speaks for itself and this actually pushes Batman to try and KILL the Joker.
- The ending of "April Moon", where the unsuspecting gang leader is about to get killed. With a drill that is slowly closing in towards the camera. If you ever had a fear of the dentist, that's bound to set it off.
- This line, as a drill bit slowly approaches the POV of the viewer:"I understand. No holding back."
- "Killed?" This guy kidnapped the wife of a cyber-doc for free augmentation for his gang, then came back to him for repairs after the poor doctor found out his wife was in on it and was cheating on him with the gang leader. He was Strapped to an Operating Table to be worked on by a trained surgeon who hated his guts and no longer had any reason to fear him or anything to live for besides revenge. IF he died, it probably came as a blessing.
- You almost feel sorry for Kneejerk, the other's upgrades failing mostly look like painful shocks, but he's left a limbless torso, staring at what's left of his arms and legs.
- This line, as a drill bit slowly approaches the POV of the viewer:
- From "Meltdown", there's the part where Victor Fries murders Stephanie Lake, his traitorous scientist girlfriend who almost got him killed on Derek Powers' orders.
- In "Spellbound", the massive insect world hallucination along with Spellbinder in general, who is a school counselor who the kids should be able to trust, but instead he uses them to steal valuables because of his ego being slighted.
- What's especially nasty is that not only does the poor woman see everyone around her as giant insects, but her own jewelry has become monstrous worms and bugs as well. Even people who AREN'T afraid of insects generally don't want to be surrounded by them or have them crawl on you.
- In "Mind Games", Tamara, the creepy psychic girl who looks eerily similar to Ace from the Justice League series, uses her powers to permanently blind the Invulnerable Man. Watching him go insane from losing his sight is pretty chilling. Especially when she could have just made him unconscious. It's made even more disturbing when it was thought to be payback for his abusive behavior.
- A similar example would be Batman's encounter with Edgar Mandragora, Steven Mandragora's son from the Justice League series, who has become a terrifying old psychic who likes to Mind Rape people until he beats them with objects or stabs them with the blade in his cane. Not to mention he eerily looks like some psychotic ghost.
- What about the episode "Rats"? Dana is kidnapped by a delusional stalker with giant rats as pets! At first he seems like a sympathetic character talking about how society rejected him for his looks, but by the end of the episode it's revealed that he's a serial killer that feeds teenagers to his rats! If Batman hadn't showed up Dana would have definitely been killed.Ratboy: [genuinely concerned] You're not eating.
Dana: Guess I'm not hungry.
Ratboy: Are you upset?
Dana: What, just because I'm trapped in the sewers with a headcase whose idea of a good time is hanging out with rodents!? Why would I be upset?!
Ratboy: [narrows his eyes at her] You're just like all the others.
Ratboy: I thought you'd understand, but you're no different.
Dana: You mean you've done this before?
Ratboy: [as his Rodents of Unusual Size start closing in] With other kids the world didn't want. I can see them all from down here. I took them away from all that and gave them a home.
Dana: What happened to them?
Ratboy: [takes out a whistle] They don't make fun of me anymore. [he blows the whistle and sics his rats on her]
- The final fate of Talia Al Ghul. She's reunited with Bruce after decades apart, having finally taken over in her father's stead after he eventually died. She's still young thanks to the use of the Lazarus Pits and wants Bruce to join her in eternal life. Talia is already dead. Its RA'S AL GHUL occupying her body, having taken his daughter's body over when his own decayed beyond use, and wants to take Bruce's as well so he can continue his legacy.
- The regional Kobra leader committing suicide rather than letting Batman catch him by jumping into a pit of snakes.
- Bane's ultimate fate; after decades of Venom abuse, he's been reduced to a shriveled, comatose wreck who needs a steady supply of Venom to survive. His handler tells Terry that at the end, Bane needed help just to make the Venom, his body had decayed so badly that he couldn't do it by himself anymore.
- Said handler OD'ing on Venom while fighting Terry at the end of the episode when he falls into a crate of the Venom patches he's been selling as a street drug.
- With his handler gone, Bane no longer has a source for the Venom he needs (though given his condition, death might be a mercy).
- Superman under mind control from Starro is frightening enough, as not only is it frightening to be mind-controlled by something you were only trying to help, there's also the fact that he flies in an upright position instead of leaning forward like he does without mind control, which would be creepy enough without taking into account the fact that that's how wasps fly, keeping their legs out as opposed to bees, who hide their legs when they fly.
- The Joker King from the comic series. He's actually Dana's sociopathic brother who's been idolizing the original Joker since childhood, and has just gotten worse and worse despite his parents trying to find some way to cure his behavior. As an adult, he organizes a massive army of Jokerz from all over the country and leads them in a huge riot all over the city that kills thousands. He's an even bigger Straw Nihilist than the Joker ever was, believing that because the solar system and the galaxy and the universe itself will eventually end, life is inherently meaningless as nothing you can possibly do will matter in the end. Unlike the Joker, he doesn't want a grand fight to the finish with Batman; he wants to kill his own family just to spite them, then die himself. He ends up killing himself while fighting Terry.
- From issue 5 from the rebirth reboot, four words: THE JOKER IS ALIVE.
- According to Paul Dini, Killer Croc was ultimately stuffed and mounted and by the time of this series he is an exhibit in the reptile wing of the American Museum of Natural History.
Nightmare Fuel / Batman Beyond