Power Rangers is normally the poster child for Never Say "Die", but it has had a few creepifying moments over the years.
Remember, this page is for describing general sources of Nightmare Fuel. Troper Tales-like nattery examples are a no-go here (see the disclaimer below).
In order for Nightmare Fuel tabs to survive, a new writing style is going to be used, nicknamed Example Lobotomy. Basic rules: just list facts as they are, don't just say "character X" or "the X scene" (such zero context examples will be zapped), spoiler policy to be determined on a case-by-case basis, italics to be applied to works' names only and not to give emphasis on what tropers say. "X scared me" is already implied by the mere addition of that example by the troper.
One early episode featured a monster called The Terror Toad with a glowing energy tongue that would wrap around a Ranger and lick his or her head, turning the Ranger into a ball of energy that would go into his mouth, and a cartoonish imprint of the Ranger's face mask could be seen on his stomach, on his first encounter with the Rangers; in the following one, he switched to a solid tongue that bodily pulled the Ranger inside. It didn't help that this monster managed to eat all but one ranger (Prior to Tommy joining the team) and left Kimberly all but powerless to stop him from eating her as well.
The Invenusable Flytrap monster that ate the Power Rangers was made worse by its voice: specifically, its usual voice was very high-pitched and reminiscent of an old lady, but it could switch to a deeper, demonic-sounding one. When it tells Heel Face Turner Tommy that it'll give the others back if Tommy rejoins the villains (and this is after it ate the other Rangers), after Tommy refuses, it says "(high voice) Fine with me! I was (switches to deep, demonic voice) very hungry (instant switch back to high voice) anyway! (Evil Laugh)"
The Invenusable Flytrap was voiced by Richard Epcar, who would actually later voice The Joker in Mortal Kombat vs. DC Universe.
An episode of the early series featured a scene where the Rangers fought Goldar and some villainess called Scorpina. After a bit of swordfighting, Rita does the whole magic-wand-grow-Godzilla-size shebang. While Goldar kept his form, Scorpina mutated into something that looked like a hybrid of the Predator, a cobra, and a scorpion, complete with dreadlocks and a fleshy whip for one hand.
It's made even more jarring by the fact that as a human, Scorpina's hauntingly beautiful. Also, her Prehensile Hair ends in a sharp hook that can latch onto an opponent and administer Electric Torture.
An early Wham Episode featured the hitherto undefeated Megazord being completely and utterly trounced by the giant forms of Goldar, Scorpina and Tommy who was still evil at the time. Moreover, a solar eclipse rendered the (solar-powered) Megazord unable to defend itself to the best of its ability. The villains suddenly foregoing the Monster of the Week premise and fighting three on one is enough of a shock as is, even if it didn't show each of the Zords sinking into lava with agonized metallic screeches.
Goldar's Dark Dimension in Green With Evil: a cage area, with the floor filled with a thick mist, with nothing else there! Outside the cage is an empty space that goes on forever, and inside there's Goldar, hunting down Jason, who is unmorphed. Jason is hiding in the mist along the floor as Goldar stabs around with his sword, nearly impaling Jason's head at least once.
In Samurai, Deker tries the same thing with Jayden (three times - the Red Ranger dodges them all here), except they're by the sea and in clear sight of one another.
All the Rangers except Kimberly becoming Brainwashed and Crazy thanks to the Dramole in part two of "Return of An Old Friend", especially the bizarre way one of them yells "Attack the Pink Ranger!"
The piranha monster from the Season Two premiere, Pirantishead, from the maker of "Invenusible Flytrap."
The season one Goo Fish (not one of Zedd's, though they share a voice actor), had a fearsome face, and after taking enough attacks started to come apart messily.
Lord Zedd himself is this trope personified; a skinned corpse with metal armor/featureless faceplate over his crotch/face that was portrayed as competently evil with the Evil Plan victories to prove it, to the point that he was toned down to reduce the scariness factor.
Lord Zedd's personal Zord, Serpentera, is powerful enough to destroy an entire planet, can fly across the Galaxy almost as fast as the Rangers could teleport, and was more or less indestructible when compared to any weapon at the Ranger's disposal. It's only weakness was it's absurd energy usage. The only thing standing between the Earth and certain destruction is not the Power Rangers, it's the time between Serpentera's next recharge.
The skeleton Rito Revolto could have gone this way if he wasn't made a comic relief character: his destruction of the Thunderzords (previously known to be indestructible) was a moment of high HSQ.
Ivan Ooze in the first movie was equally as scary, despite being more camp than Lord Zedd was at the time: in one scene where the kids of Angel Grove are partying down with Ivan's Ooze while their parents are mindlessly wandering to the quarry to "leap to their doom". Said Ooze was advertised and sold by Ivan while wearing an outfit reminiscent of that worn by Merlin in Merlin's Shop of Mystical Wonders.
The episode where those two guys are working in a cab service and then the villains zap their cab so that it turned into this freaky mutant monster cab thing called Crabby Cabbie. Said guys got stuck in its stomach.
The episode of Power Rangers Turbo where the rangers got shrunk, although large amount of it was played for comedy (the rangers got trapped in Divatox's closet at one point).
Adam was fooling around during a ride on a torpedo and nearly got killed.
Lost Galaxy had one episode featuring an Elvis-like lobster thing that after drinking a potion became a much more dangerous, and more monstrous, creature. He was called Radster, from the first episode. He proceeded to smack-talk with the Red Lion zord, then got blown up.
The arc of Lightspeed Rescue in which Ryan gets a cursed "tattoo" burned into his back by the Big Bad, and whenever he morphs the tattoo moves up his body even more, until it reaches his neck, at which point it will kill him. The tattoo moved during a Nightmare Sequence, too.
Frax's death in Time Force was a Dies Wide Open involving a scream and parts of his robotic face falling apart. This after his having been reprogrammed into a mindless automaton by the Big Bad.
Cole's parents' Family-Unfriendly Death, as shown in flashbacks in Wild Force was something that shouldn't have gotten past the censors. Saying "kill" just won't fly, but having vines assault and grow through the bodies of two terrified humans is hunky-dory so long as no actual blood is shown. Allegedly, writers told Fox standards and practices the parents were going to come back just fine. The show was in the middle of transferring to Disney's control, and standards and practices folks there did not see earlier episodes and merely assumed they were dead the whole time.
Ninja Storm has a cyborg villain suffer melting at the hands of another, treacherous villain. His half-slagged body is seen in a rare exception to PR's Everything Fades tendency. His executioner quips that he was "having a little meltdown".
RPM has one of the main characters tearing Mecha-Mooks apart off-screen, in the first episode. As he leaves, we pan away to see the carnage, complete with the lower half of one of the mooks stumbling on-panel before falling lifelessly to the ground. That perfectly illustrates the Darker and Edgier tone of the entire series.
In the final arc of Mystic Force, the Master has been incubating in the body of one of his followers, who has had a change of heart and intends to spend eternity in the "sleeping lake" to prevent his return. Just when it looks like he's about to succeed, he's prevented from reaching the lake by another villain. The Rangers, and the audience, are treated to the sight of the Master's hatching from him: parts of his body swell before tentacles burst out of him from within, causing bluish ichor to fly. Finally, his body bursts apart and falls about the Master's heretofore-unseen true form like an empty sack. Then, the Master promptly subjects one of the heroes to Mind Rape, making him experience his own death at the Master's hands/tentacles. That scene was in its source series as well.
One of Overdrive's main villains enhances some monsters by reaching into their chests and leaving devices inside that revive them as cyborgs; those monsters were typically defeated and unconscious at the time. Even though beaten Rangers monsters usually don't leave behind a body, it's still not too much of a jump to think that the villain is reviving a monster corpse, although the Chillers he tried it on were still standing; on the other hand, foot soldiers can't take the upgrade as they start twitching, then their customary babbling noises get louder and faster... and then they burst apart, becoming an indoor mini-snowstorm.
From the same series, it's subtly hinted across several episodes that Mack, the Red Overdrive Ranger, isn't human. The Reveal happens when this character finds himself as a talking severed head lying on a table. Turns out he's an android and his "dad" must finally explain (Rangerboard dubbed him "iMack" fairly quickly afterwards).
Camille got A Day in the Limelight, and Flit (aforementioned commentator) urged her to go into a pizza parlor (the Rangers' pizza parlor, though he didn't know) because he was hungry. "Eat something, so I can eat something!", as Flit says, implies he survives by eating Camille's partially-digested food.
Any time a series' Megazord gets destroyed is scarring, but the most heart-rending is the destruction of the Thunder Megazord and the White Tigerzord. The White Tigerzord's head falls off before the body, trailing wires and sparking, and collapses backwards. The Thunder Megazord stretches an arm out imploringly - the other falls off, then the entire zord falls apart bit by bit.
Fridge Horror sets in as you realize nearly all Zords carry a degree of sentience...
From Power Rangers in Space, almost anything with Darkonda counts: his debut episode, where he infected Carlos and Cassie (the black and pink rangers respectively) with Barillian Bugs, caused them to turn into giant human-sized versions of the bugs. In Flashes of Darkonda, when he proves himself to be The Starscream, Ecliptor decides he needs to be removed and proceeds to poison his new Super Serum, turning it into a Psycho Serum. When Darkonda takes it, he beats up on the Rangers for a while, and then starts screaming in agony and terror, trembling, with streams of yellowish liquid oozing and spraying from his pores: he eventually mutates into a truly hideous form, and a giant chunk of his flesh falls away, turning him into a new monster. Oh, and he has nine lives.
In his second appearance, he forcibly merges himself with Ecliptor, turning into Darkliptor.
The final episode of Turbo had Divatox leading an army of mooks to destroy the Command Centre, and the Rangers desperately (but uselessly) trying to fight them only to lose, running away into outer space for their life.
This ad for Power Rangers toys appeared in the beginning of some MMPR tapes. Aside from the prospect of Megazord crashing through the wall, viewers saw it coming at them from head-on.
During the first season, there was an episode where the Yellow Ranger's cousin was turned into a flat, cardboard cut-out of herself, courtesy of Pine-octopus.
The Psycho Rangers were unbelievably awesome, but everything awesome about them was scary as well. Psycho Pink she gets grazed in the eye by a lightning blast from Psycho Yellow, and they later exploit this to weaken her, revealing a freaky eye underneath that helmet before she turns into a massive plant-tentacle monster; then Psycho Blue pretty much almost kills the Blue Ranger, and after they trick him into driving his teammates away, he goes into a flurry of Unstoppable Rage slashing on all the Rangers. Then there's the Paranoia Fuel of them being able to trace the sound of the Rangers morphing and even their voices, popping up when they least expect it, and Red's unbridled ambition to kill the Red Ranger, resulting in another shot to the eye, with a laser. The Psychos also start off as the Evil Twin group of the good Rangers, but by their end the Psychos all have the ability to transform into hideous monsters. Having also appeared as actual teens at some point implies You Cannot Grasp the True Form. Towards the end of the arc, Red, Yellow and Black became obsessed with killing their respective opposite colour Ranger, and even attacked each other over it. Finally, when they return in the Lost Galaxy team-up, Psycho Pink actually succeeds in killing one of the Rangers, albeit temporarily.
Mesogog, the main antagonist from "Dino Thunder" was one of the few villians that didn't have an ounce of comic relief in him, even going as far as to mentally torture who failed him.
That monotone of his was scary as well: He never raised voice, not once. Creepy Monotone all the time. He did get significantly crazier after he separated himself from Anton Mercer, however.
In Wild Force, Toxica was tricked into cutting off her horn, which weakened her to the point of being unable to stand up. Soon after, Mandilok avoided a shot from the Jungle Blaster by using her as a human shield. She disappeared in a cloud of gold glitter and died, despite being the only human-looking org in the season. Mandilok carelessly taunted Toxica as she died screaming in agony.
Ransik, the Big Bad of Time Force, has what looks like the ability to pull bones from his body and turn them into swords. In the Wild Force/Time Force team-up "Reinforcements From The Future" we see exactly how he got the ability to do that: he frees the life essences of three fossilized Orgs, who literally jump down his throat and copy his DNA to create their new bodies. There's also the horrific disfigurement of his face and the liquid-mercury boils that erupt from his body when his disease flares up. During the Season Finale for Time Force, he takes out all the Rangers by simply punching them before pulling a Heel-Face Turn, which is the only thing that spared the rangers.
Pumpkin Rapper has the charming ability to encase the Rangers' heads in pumpkins, leaving them unable to breathe.
The final battle of In Space has Zordon dying, before he releases a wave of goodness that destroys evil. Sounds good until after destroying a few groups of monsters we see it heading towards Rita and Zedd, the amusing and lovable, though always effective, villains we've spent the entire series growing fond of are now faced with an inescapable wave of flaming death rapidly approaching them as Rita screams in terror for her husband to not let it get her. Thankfully everything ended up all right for her and Zedd.
Retcons actually make the purification of Rita and Zedd quite horrifying. Operation Overdrive shows that, while evil, they had a son, only a year or two prior to their purification. A son that wasn't purified with them, who continued to be a villain, and who seems to treat them as having died in the purification: a kid whose parents, one day when he was two, just left to go to work, and came back as unrecognizable, completely different people.
One more from Mighty Morphin: Rita's War Zord Cyclopsis, from Doomsday. Rita brings her palace to Earth, giving her the power she needs to raise it from the mantle. It was scary enough to make the Megazord's knees tremble. It took the Ultrazord to beat it.
RPM's "Alphabet Soup", where people could very well be kidnapped and put to work by their own government for being too smart.
Another RPM example is Ranger Yellow's backstory: the killer robots came on her birthday and she had to walk through the blasted wastelands alone.
The villains have forced labor camps, and perform experiments in cyborg creation on the laborers. A Nazi by Any Other Name, indeed.
In Power Rangers in Space's "Dark Specter's Revenge", the feud between Ecliptor and Darkonda came to a head when Darkonda had Ecliptor captured and forcibly brainwashed in the middle of the night. To elaborate: one night, a bunch of Quantrons sneak into Ecliptor's quarters and drag him away, kicking and screaming, and strap him to a metal slab, where Darkonda comes out, dressed in full Torture Technician regalia, and cackles, "You need a little attitude adjustment! Say AH!" The last thing we see before it cuts to credits is a menacing-looking spinning drill/claw/thing steadily moving towards the camera, about the slice into Ecliptor's face. Somehow, having it happen to a villain makes it even worse: this isn't like when the Rangers get captured by the bad guys, and The Cavalry always comes to bail them out by the end. Ecliptor, one of the most sympathetic villains on the show, is tortured and brainwashed until he doesn't remember ever having loved Astronema. Even for a villain, that's pretty damn harsh.
And then, shortly before his own demise, he witnesses Andros accidentally kill Astronema/Karone and briefly laments how he "loved her like a daughter" indicating that the brainwashing either didn't completely eradicate his soul or has worn off by that point. Alas, Poor Villain
The Lizinator. Even the goofy "Ah-nold" voice doesn't quite gloss over the fact that he's pretty much INDESTRUCTIBLE, to the point that the Rangers have to summon a special Zord that's basically a giant cannon on wheels to take him down. But not before he beats the Red Ranger half to death behind the school in the middle of the day, while everyone is still attending class.
Most Power Rangers villains, as menacing as they may be, have a softer, sillier side to them, for example, Lord Zedd's mellowing out, or Ransik's love for his daughter Nadira. And then there's Mesogog. Never once during the entirety of Power Rangers Dino Thunder does he show the slightest traces of compassion and humanity(barring a single occasion where his human half intervenes on behalf of his adopted son- whom Mesogog himself is about to torture), and when his subordinates fail him, he doesn't throw a tantrum, he doesn't scream about how much of a headache he has- oh no, he tortures them via Mind Rape. Adding to his general creepiness are his unsettling monotone hiss,and just how well the facial prosthetics used for him work.
Venjix, who manages to wipe out every single human being on the entire planet except for those in Corinth. And even a significant portion of those are his sleeper cells.
Another nasty piece of work is Dr. Viktor Adler/ Master Org. To elaborate: Dr. Viktor Adler was once a respected scientist who worked with Cole's parents Richard and Elizabeth Evans and secretly had a crush on Elizabeth, but after Cole's father proposed to her and took the spotlight during the press conference on their research, Adler became driven by jealousy and sought revenge against them. So what did he do? He took seed of the original Master Org, become an Org himself and proceeded to kill Cole's parents and would have killed Cole(who was just an infant, by the way) if he had found him. What makes him even worse is that he is the first human villain who actually chose to become evil, all other human villains before were either brainwashed and didn't have control over their actions or had sympathethic qualities(like Ransik). He willingly became the second Master Org so that he could murder two innocent people who saw him as a friend and meant him no harm in the first place(They didn't knew that Adler had a crush on Elizabeth and Richard even encouraged him to speak during the press conference), out of a petty grudge, while claiming that it was his rightful revenge. All these things make him one of the most vile, malevolent villains in Power Rangers universe, with only few villains matching him in terms of evil.