!!From the books:

* The Nazgûl, ''especially'' during the Siege of Minas Tirith. Tolkien's descriptions of these undead ''things'' terrifying the inhabitants of the city into hopelessness really grinds in how desperate the situation is.
** The Witch-King definitely stands out just for this. Even without the film, the description of his 'face' is horrifying enough.
* Combined with above, the Dawnless Day. A huge cloud comes out from Mordor, stretching as far as Rohan, plunging all of Minas Tirith into darkness.
* In the chapter "Scouring of the Shire," it is implied that Saruman forced the starving Grí­ma to eat the hobbit Lotho Sackville-Baggins.
* The Barrow-wight scenes. The hobbits get lost in the mist, hear voices calling to them... and the next thing Frodo knows is he's waking up in a ''grave'' and there is ''something'' in the darkness with them... terrifying!
* Everything about Gollum. Not just his ghastly appearance, but knowing that it was his addiction to the Ring which turned him into whatever creature he has become, and the lengths he will go for the Ring. The movies make it worse by giving him a split personality.
** Gandalf also mentions that during his search for Gollum he began to hear rumors of a blood drinking ghost who [[ChildEater "climbed trees to find nests and crept into windows to find cradles"]].
* "[[BeneathTheEarth Far, far below the deepest delving of the Dwarves]], the world is gnawed by [[UltimateEvil nameless things]]. [[BiggerBad Even Sauron knows them not]]. [[TimeAbyss They are older than he]]. Now I have walked there, [[TakeOurWordForIt but I will bring no report to darken the light of day]]."
* The concept of The Ring itself. As the SoulJar for the most utterly evil creature to ever inhabit Middle-Earth, it's [[BeautyIsBad beautiful]], you want it even if you don't know why, it stretches out your existence but in a bad way, it whispers to you and puts ideas into your head, and if you spend too long with it, it will pervert you into a [[TheCorruption horrible shadow of your former self]], leaving you a hopelessly addicted, twisted, pitiful wretch. How long it takes to do this to you depends on your mental and moral strength, but it will break you eventually no matter how strong you are. If you're not particularly strong-willed it can claim you in mere seconds! And if it ever achieves its goal, [[TheEndOfTheWorldAsWeKnowIt then...]] No wonder people who don't buy Tolkien's protestations against the Ring being allegory have compared the Ring to everything from capitalism to communism to nuclear power.
** The fact that there are so many things in RealLife that ''can'' be compared to the One Ring... now there's some NightmareFuel for you.
* "She, who only desired death for all others, and for herself a glut of life, alone, swollen until the darkness could no longer contain her and the mountains could no longer hold her up..."

!!From the film version:

* Bilbo Baggins' completely ''[[NightmareFace pants-wettingly out-of-left-field freakout]]'' when he realises Frodo has the Ring. It really does come out of ''gracious nowhere''.
** Try pausing the film on that moment and moving it back and forward, frame-by-frame. It makes it inexplicably more horrifying.
*** Because, if you look closely for that fraction of a second, he [[TheCorruption becomes Gollum]].
*** [[http://media.tumblr.com/tumblr_mewy6yNRM01qleu8g.gif In case you wanted to not sleep tonight...]]
* '''[[GiantSpider SHE]][[AnimalisticAbomination LOB.]]''' That would have been an ''excellent'' time for a SpecialEffectsFailure, but nooo, you Weta [[MagnificentBastard bastards]] had to have ''[[VisualEffectsOfAwesome standards]]...''
** Blame this one on Creator/PeterJackson himself. He's an arachnophobe, and he used this to full effect to make the scenes with Shelob as frightening as possible. The part that was especially creepy was where she was following Frodo ''silently from above''.
*** Equally worse, earlier when he was in the cave, you ''just know'' she was watching him.
* The [[BrownNote screech]] and VertigoEffect combination when someone encounters a Nazgûl for the first time.
** Which is actually the voice of Peter Jackson's wife, largely unaltered. Maybe we should be thankful that she prefers to keep to herself.
* The Balrog, in Moria? Feh, that is [[NothingIsScarier NOTHING]] compared to Gandalf reading the final diary entries of the mine's dwarves. "[[ApocalypticLog Drums...drums, in the deep...we cannot get out...]]''[[KilledMidSentence They are coming-]]''"
** Right then, of course, Pippin knocks a skeleton down a well, making all kinds of racket. After a tense moment of silence, Gandalf scolds him, then turns to leave. And then...
-->''[[HellIsThatNoise boom]]''
-->''[[OhCrap BOOM]]''
* Mordor. One actually wonders '''how it got that way'''.
** The heck with that, one wonders what Sauron's massive armies are ''[[ImAHumanitarian eating]].''
*** Actually, it has been established that Mordor does have some fertile lands where the Enemy grows food for the orcs.
* Imagine being there before the battle of Helm's Deep, when 10,000 Uruk-hai are standing before you in the dark and the rain, armed to the teeth, then start smashing their spears on the ground in unison and screaming at you. The atmosphere was captured so beautifully, it's no wonder everyone looks about ready to shit themselves.
* While the Witch King was quite badass in both the films and books (and also the game he was in), one [[http://images.wikia.com/lotr/images/b/bb/Grnazgul_021_Nazgul.jpg cannot help but become slightly unnerved when he removes his helm.]]
* When one puts on The Ring, they turn invisible. It's because you enter a shadow dimension where the only other one there is the '''DARK LORD OF ALL EVIL'''. It's AloneWithThePsycho on a cosmic scale.
** To say nothing of what [[GodOfEvil Sauron]] says to Frodo when he puts the Ring on in The Prancing Pony:
-->''"I see you... You cannot hide from me. There is no life in the Void, only death."''
** In that vein, the second time Frodo puts on the ring, he sees the faces of the Nazgûl, all horrifying death rictuses.
* Galadriel's temptation by the Ring, with absurd amounts of reverb on her voice as she declares herself "Beautiful and terrible as the morn! Treacherous as the seas! Stronger than the foundations of the Earth! All shall love me and ''despair!''"
* After Frodo tells Sam, "[[WhamLine The Ring is mine]]," there's [[SlasherSmile something unsettling about his smile]] before he puts the Ring on. Which makes sense, given that [[TheCorruption the Ring has just seized what could have been permanent control of Frodo.]]
* In the extended edition of ROTK, we get the Mouth of Sauron. Most unnerving set of teeth ever, with a creepy voice to boot.
* The [[ExactlyWhatItSaysOnTheTin Dead Marshes]]. The description was creepy enough in the book, but in the movie the dead look like underwater, ethereal zombies.
** Then as Frodo approaches the water and looks down at one OH DEAR GOD WHY DID ITS [[ProphetEyes EYES JUST OPEN]]?!
** They're even more haunting, in both versions, if you recall that [[RealitySubtext J.R.R. Tolkien fought in World War I and likely had very vivid memories of the flooded bomb craters filled with corpses.]]
* Emiliana Torrini's "Gollum's Song" from the ''Two Towers'' soundtrack definitely counts. It's a nice, sad, mildly creepy ballad from Gollum's perspective... until the end, when suddenly she hisses in a gravelly voice, "Kill them all!"
* Gandalf trying to lift Saruman's power on Théoden becomes very creepy indeed, when Saruman starts speaking ''through'' Théoden.
* The scene from ''Return of the King'' [[http://www.youtube.com/watch?v=ep0t0sK6MGw where we watch Smeagol slowly turning into Gollum]]. Though the FX mildly alleviates it, since it's really easy to tell it's just makeu- [[spoiler:OH GOSH HIS EYES GOT BIGGER!!!]]

!!From the animated version:

* The Stone Watchers at Cirith Ungol. Especially the way their expressions change offscreen. The worst is their mocking smirk when the Phial doesn't work on them on the way out. They're worse than the frakking [[Series/DoctorWho Weeping Angels]].

!!From the videogames:

* Bilbo's picture at the beginning of the GBA version of ''FellowshipOfTheRing'' is basically the evil face he makes in the movie's freakout, AS A FREEZE FRAME. Have fun playing the game.
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