The thing that Ed and Al created trying to bring back their mother. All those twisted limbs and the pulsating and the horrible gaping mouth and theeyes... Ugh.
Plus that moaning, strange noise. Like it was trying to talk or something. That creature's one of those things that evoke the 'thing that should not be / What is that ?! God, just kill it!!' feeling.
The thing was actually Al. It probably was trying to talk, considering what it was seeing - Ed looking completely broken and horrified, bleeding out of where his leg used to be, calling for his mother. No wonder it reached out to him…
Pinako saying that she buried it in the Elric's back yard. Oh god was it alive when she buried it and if not, when did it die and how did she even bear to go near that thing and IS IT STILL IN THEIR BACK YARD AND AAAAAARGH!
It's later revealed that it was actually Al put into that disgusting body, and it was simply PURE CHANCE that his soul wasn't permanently trapped in it!
Shou Tucker himself. The very thought that a man could transmute his wife, and later his five-year-old daughter, into chimeras is just... nauseating in all sorts of ways. From Nina's garbled speech, she wasn't even fully aware of what had happened. And then Scar shows up and Mercy Kills her.
What makes it worse is that it was pointless. The military has already created Humanoid Chimeras, FAR better ones than Shou's creations, What a Senseless Waste of Human Life.
Ed's scream of rage and powerlessness at the end of the scene just made it so much worse.
Ed's nightmare after this is turned Up to Eleven in the Brotherhood anime, resolutely crossing in High Octane Nightmare Fuel territory. It features a front view of the Nightmare Face of Resurrected!Trisha, while in the manga, it's only Normal!Trisha with Blood from the Mouth. And the voice change is kinda scary, too.
If anything, the second game based on the first anime manages to make this just as bad, know Resident Evil? You'll be getting familiar vibes walking through the mansion, but not through zombies, you'll be looking at the files, and when you look at Tucker's diary, it's clear that he's lost it, you can see them here.
What made it infinitely worse is that he tried to play it off as Not so Different.
The fate of first Greed. He got melted down to his core....slow and painfully. To make it worse, the Big Bad DRANK THE DAMN THING!" Greed's reaction to this? Insane laughter.
The making of the Philosopher's Stones...Which involves getting your soul ripped out and trapped in a tiny, rock-sized container... along with probably a dozen more souls. And you are conscious. The whole time. Those screams of despair aren't there for no reason...
Maria Ross' death. She gets flame broiled by Mustang in episode 17, and her burnt corpse is very graphically displayed. It was actually a cadaver created by Mustang, but still...!
Every single time Gluttony stares at the screen, whose idea were those scenes?
Envy's true form. You think the idea of turning souls into Phlebotinum is scary? Try seeing their distorted faces begging you for release from their tortured existence. A melting, dripping, mutating bodymash of emaciated faces begging for their mommies and/or death. OHGOD.
One of them kept saying "Big brother" over. And over. And over.
It's not just those faces on its body, but they are also on its tongue and they reach out and grab whoever its trying to swallow with grotesque arms! The fact that one of its eyes has multiple pupils is pretty creepy as well.
The true form is Upped To Eleven in the anime. It's the way that all the faces are moving, all the time...
Envy's Sleep Mode Size. It's particularly abhorrent and uncanny. Looks like the hybrid of a maggot, a human fetus, a caterpillar, and some wide-eyed fish. It also somewhat invokes Vagina Dentata.
The disturbing imagery gets turned up even further in Brotherhood in the scene where Marcoh defeats Envy. Misshapen heads vomiting out misshapen heads and tortured screaming.
Here's one to think of that's especially horrifying and tragic—when Envy seizes Marco, one of the souls attached to Envy is a baby which grasps Marco's shirt and wipes its mouth on it.
Gluttony's true form is shown several episodes/chapters before Envy's. His entire front half splits open, baring his open ribcage, which extends from his jawline to his groin and rakes forward. His entire lower jaw is gone, leaving tusk-like ribs near his jawline, and his exposed, Orobouros-tattooed tongue slavering in the open air. Looking inside the opening reveals nothing but inky blackness and a single eye, exactly like the one in the Door of Truth. And then he goes on an insane rampage, erasing large sections of the landscape with what appears to be some sort of Kamehame Hadoken, but is actually him extending his ribcage faster than the eye can see and swallowing whatever he catches. From the most cheerful, childlike, and seemingly least dangerous and malicious Homonculus, this was a nasty surprise.
And then he eatsEd, Ling, and Envy, and we're treated to an inside view of his stomach; or rather, where everything he eats goes. It is an infinite, featureless plane, with chunks of all the evidence, ruins, and people Gluttony's ever eaten still intact inside. The plane is filled with a similarly infinite ankle-deep sea of blood. Worst of all is how, as Envy fatalistically explains, there is no way out. None. The place is another dimension: literally infinite. The only thing normal people can do is wander in the sea of blood, waiting to die. Ed finds a way out, but that method isn't pretty either, and if it weren't for Envy's Philosopher's Stone, probably fatal.
What adds to the horror is that it was pure luck Ed happened to notice the alchemical mural.
Pride, what with all the giant mouths and eyes. And the anthropophagy. And the homunculus cannibalism.
Here's one in the manga that is more psychological horror than a scary image, but still pretty scary. Riza discovers Pride's identity. Pride is a Living Shadow of eyes and mouths and likes to rip people to shreds or eat them (that's the visually scary part). What makes it even scarier, is that Pride can basically appear anywhere there's a shadow, so for several scenes, Riza is paralyzed with terror just by seeing a shadow near her, as Pride could devour her at any time and could hear everything she said. Luckily, she is able to pass a coded message to Mustang and escape from this, but it's still pretty horrifying.
It's even worse in Brotherhood, complete with exceedingly ominous background music and Pride's warped, echoing voice... "I'm watching you from the shadows."
And all those Slasher Smiles after eating Gluttony. Enfante Terrible indeed. More so in Brotherhood than the manga, since apparently Studio BONES learned a bit when they animated Soul Eater; he grins like Medusa.
Especially in the anime, where he ABSORBS KIMBLEE...ALIVE. Worst part is, you watch it from Kimblee's point of view, and those jaws... those horrible jaws... then... CHOMP.
What about his Sleep Mode Size in chapter 106? A tiny, tiny human baby, so small you could fit it on your palm, saying 'mama' all over and over... and if you were unwary enough to touch it with your bare flesh it would probably be able to take over your body.
What happened in Hohenheim's backstory. Waking up to discover that you're the only one still alive in your ENTIRE COUNTRY, have been manipulated into practically causing genocide and thus share responsibility of the horror- and then discovering you've become immortal and the souls of half of the inhabitants of your country are within you, screaming in pain, sorrow and anger every minute? The Scream says it best.
Or the Cyclops soldiers, which look like the unholy spawn of the Mass-Produced Evas and an especially ugly zombie?
The Brotherhood anime has them all awaken with a chorus of horrible screeching. Like millions of souls screaming of unexplainable torture. Equally disturbing is their tendency toward creepy giggling and Psychopathic Manchild behavior which along with some of them calling for their parents strongly implies the ravenous monsters contain children's souls.
When Envy recreated his body using those said Cyclops soldiers. They basically devoured each other and then formed an abomination/blob.
Father's 'true' form in chapter 97. The black thing with huge eyes all over of his 'body', the mouth, and how the black goo-thingy came out of his body. Like this.◊
It's even more horrible in Brotherhood. Especially with those voices.
Chapter 102, when the Homunculi force Roy to open the Gate, and he loses his eyesight even though he didn't do anything.
Mustang: "What are you talking about? Are you with me, Fullmetal?"
Ed: "Huh? What are you talking about..."
Mustang: "It's pitch black... I can't see a thing. Where are we? Can you see any lights?"
Some bonus Fridge Horror: Can you imagine what the last few chapters must have been like? He's totally helpless and can't see what's happening while a) the epic battle continues, b) he gets picked up, dragged across the room, and used to rip a gaping hole in reality, c) Father throws a freaking sun at them, and d) the free-for-all fight resumes. He can hear everyone fighting around him (kids fighting around him, even), hear what horrible things are happening... and can't do anything, even to protect himself. Now that's nightmarish.
The... thing... which was created from Pride using the Gold-Toothed Doctor as 'raw materials' for the transmutation.
The Blind Alchemist Gaiden/OVA. Not just physical horror, either. The sheer psychological shock is pretty disquieting as well.
Everyone is dead. Everyone. Havoc? Breda? Falman? Fuery? They're dead. The Briggs soldiers in Central and in the East? Dead. Winry? Dead. Pinako? Dead. Gracia and Elysia? Dead. The Ishvalans, the people in Rush Valley, the Youswell coal miners, every cast member that has ever made an appearance in the series is dead, their souls stored inside a monster. Their bodies? Empty. These characters that you have grown to love are dead. And there's nothing you can do about it.
Chapter 105 revealed this not to be true. They are, in fact, still alive. However, their apparent deaths at the time was such a terrifying moment, that the above comment is still warranted. Because the reader has not much choice other than to believe it at the time.
In Brotherhood, they show the Ishbal Massacre, why is this reminiscent of the war? The State Alchemists eyes and hair are Blue and Blond, Nazi Subtext, much? The parts that show the Ishabalan civilians being trapped in the city and mown down mercilessly while they scream for help (particularly images of the children being shot to pieces) is very haunting. The music and Deliberately Monochrome effect do not help.
The Nazi allusion was emphasized when the Ishbalans wanted to flee to another country to escape the genocide but where denied that by these countries.
Word Of God says this was inspired by the Ainu. That stuff has probably happened in real life.
In the scenes in the decaying, bombed out shell of a city. That's WWII era London. While that may not seem so disturbing, bear in mind that in the first anime series, it is said that every time alchemy is performed, someone in that world dies. Even if the manga/Brotherhood 'verse works differently, it's still creepy.
"What if I was to give birth to humans?"
It gets worse: the humans he means? Hohenheim's friends from Xerxes.
Izumi looking down at the tiny baby touching her foot.
And then Father proceeds to nuke them all into oblivion. Those poor souls have been trapped for centuries in an endless torrent of crazed, screaming companions, only to abruptly obtain freedom— giving them just enough time to see the world, and then be blown away to nothing.
In chapter 106 of the manga, Pride's body is slowly falling apart from forcing Roy to open the Gate. So what does he decide to do? He makes a cut on Ed's face and forces his shadow arms inside to take over Ed's body as a new container. You can see the shadows force their way inside and slowly spread across Ed's face and shoulders.
The Brotherhood version, where he gives his speech, then uncovers his eye to reveal that half his face is just a gaping hole into a raging storm of tormented, screaming souls. And then some of his shadows stick out of where his eye socket should be!OWOWOWOWOW. It's heavily implied that Pride feels no pain from that.
In chapter 107, Ed finally regains his right arm. This is a good thing, right? Except... if you look closely, you can see there are now automail parts fused into his flesh where the arm regrew — look at his right shoulder.
Father's original form, "The Dwarf In The Flask",because it seems like he's the embodiment of pure evil, and you don't even expect or even know it, more or less, it's somewhat frightening.
Father getting trapped in the gate by Truth. The Brotherhood episode came out, and watching Truth talking with a cold indifference while Father gets pulled in complete with him screaming and sobbing, asking for repentance.
Then there's Envy's turn to get burnt. The man known as Roy ceased to exist for a few moments, replaced by some wild primitive beast man that happened to look like him. Though he was talked back to his senses.
The moment in chapter 107 when Greedling punches God!Father in the eye and it shows HIS HAND STUCK IN HISEYE-SOCKET also deserves mentioning. Nerves seem to be traveling from said eye-socket, under Greedling's skin, and UP HIS ARM TRYING TO TAKE THE PHILOSOPHER'S STONE WITHIN HIM.
Episode 41. The scene where Ed gets gored through the stomach by the beam. Edward's bone-chilling screams of pain as the Chimeras pulled it out of his stomach as he simultaneously healed himself. He was burning through his soul to do so. This with him screaming in agony and trying desperately to focus through the pain for just long enough to seal his wound.
The Sacred Star of Milos. There was one hell of a cure for insomnia when the man we thought to be Long Lost Sibling of Julie Crichton, Ashleigh, reveals that he was actually a former bodyguard who murdered her parents, ripped off skin with the tattoo of half the Milos transmutation circle and the face of her brother and grafted both of them to his body. This was just after he impaled her friend and his underling with a sword that opens up to drain their blood so it could fill the city wide 3 dimensional transmutation circle, and before he tore off skin with the tattoo from his body so he could match it up with the one on her body. And we later find out not only was her real brother fully conscious when his face was ripped off, but he survived it when he appeared to give his identity thief a very painful death. Everyone in the room cheered when that happened.
The Gold Tooth Doctor's creepy Slasher Smile, from one of the most depraved characters in the series. Not only did he make the failed Wrath-wouldbes monsters, the bastard slit Riza's throat, nearly killing her.
First anime
Shou Tucker's reappearance as a chimera. HIS SPINE WAS FUSED TO WHATEVER ANIMAL HE WAS COMBINED WITH IN A WAY THAT MADE HIS HEAD LOOK UPSIDE DOWN.
And the fact that Shou talks entirely in a WHISPER after this event.
If you think about it, Tucker's fate in the anime may be more poetic and horrifying than just dying. Now he's that giant, upside-down dog thing, totally insane, trying to bring Nina back from the dead. The last we see of him, he's sitting with the soulless, empty Nina doll in a dark room, scribbling things on the walls, ceiling and floor, talking to her as if she's there.
Also there's all the freaky shit from the first episode of the series! When Al and Ed were in the Gate and Al was being forcibly pulled in, screaming for his brother to help him while Ed reached for him. Their hands barely touch for an instant and then Ed is screaming in disbelief, anger, and then bloodcurdling pain as he clutches the bloody stump of his leg.
The chimera that Father Cornello put together to resemble Rose's boyfriend.
The time when Wrath, pre-"awakening", accidentally fused himself with his bed... It's a bit like the Tele Frag article when you think about it.
When he was fused with Sloth and Edward transmutes his mother's remains into their fused bodies and transmuting her so that she is literally dissolving while Wrath is screaming profusely for "Mommy".
Envy kills Edward via a fist through the chest with blood spewing everywhere. Top that off with a close up shot of Edward's pupils dilating as he finally dies. And Envy's freaking huge Slasher Smile as he was doing so.
The Mind Screw moment of when you see the flashback of Izumi trying to bring her baby back to life: It looks like the transmutation worked as her baby's corpse swells up and actually is crying but in reality it failed as she places the baby at the gate and those creepy shadow arms grab it and yank it back through the Gate. Izumi is then seen with blood dripping from her mouth.
Kimbley's method of dispatching his foes or just people who happen to be in the wrong place at the wrong time.
The death of Basque Grand at the hands of Scar. After Scar deconstructs his gray matter with alchemy, blood shoots out of his ears, nose and eye sockets in slow motion.
In Curse of the Crimson Elixir the Elric brothers are sent to investigate the village of Bord'wan with Riza. You find the place in complete shambles—all the houses are blown out and many are covered with bloodstains (even the path you're walking on). It's dark as night, infested with scores of inky-black, zombie-like Golems, and has some suitably creepy music in the background.
Near the end of the game Ed's contact with the Crimson Stone causes him to end up in a blank white void. His only guide are blinking red lights, and touching them allows him to see Crowley's memories of his slow and steady descent into complete madness after failing again and again to create the perfect golem body to place his lover's soul into.
"Aw, come on, Lust! Isn't it about time you let me eat the old preacher?!"
There's the episode where people in a town are infected with a disease that slowly kills a person by turning them into stone. Made all the worse with the close up of one of its victims: A sweet, fairly pretty young woman has her face gruesomely disfigured so it resembles rotted, stony bark.
The whole thing with being stuck inside the Gate. Wrath described it pretty well. Stuck there. Sentient. No way to escape. ... and now lets think about Al's body being there, surrounded by all those eyes...
Envy and Hohenheim in the movie. Especially the whole hanging up there, having something pierced through your body, waiting for finally something to happen...Highly unsettling, especially considering the time period Hohenheim hung there in Envy's mouth!
The expression on Mustang's face as he is ready to kill himself in the Ishbal flashback episode is nothing short of haunting. Here it is.
To specify just part of it: In episode 8 he kidnaps both Winry and Edward. He has Ed tied to a chair with his automail arm taken off and has Winry Bound and Gagged. He graphically talks about how he likes slicing people into pieces and makes several Nightmare Face's. He slices Edward's arm and mentally tortures him, while trying to murder him. Seeing Ed crying and screaming makes it especially bad. Those kids really need therapy after that.
Martel's death in this version. It's roughly the same as in the manga, but the most major difference is that the actual killing is shown from Al's point of view. Also, Al told her to hide in his armor to get away from the military.
Hughes' death is also only a little different in this version, but in a way that largely changes the atmosphere. The part with Lust is mostly the same, it's when Hughes goes to call on the phone in the lobby. The random girl he runs into is replaced with the Fuhrer's secretary, who is the anime's version of Sloth, who also tries to kill him. It gives it a kind of Paranoia Fuel feeling, like the Homonculi can be anybody and anywhere, and there's nowhere to run.
That horrible, inside out thing that Ed and Al made? In this version it lives on and eventually becomes Sloth. It's still horribly creepy as ever.. There's concept art for it too if you want to see how horrific it is in depth.
In episode 14 when Scar kills Basque Grand. His head essentially explodes, though not enough for it to split. Scar does this right in front of Ed.
Unsorted
The protagonist very graphically loses an arm, a leg, and a brother, and sees a monster instead of the mother he was trying to raise from the dead all within the first minute of the series? It could only get worse. And it does - with the fate of Nina, Shou Tucker, the events at Lab No. 5, to name a few, all supplying a lifetime's quota of nightmares.
He didn't even see a "monster", but a pile of incoherent flesh that looked like someone took a human and turned him inside out.
Just the sight of The Gate itself, let alone what's inside or beyond it it is terrifying.