The Avengers (film)/Nightmare Fuel

The Marvel Cinematic Universe film
"Loki: I won’t touch Barton. Not until I make him kill you slowly, intimately, in every way he knows you fear. And then he’ll wake just long enough to see his good work. And when he screams, I’ll split his skull! That is my bargain, you mewling quim!"
 * The scene in which Natasha interrogates Loki, and in an incredibly menacing speech, Loki punches his cell wall so hard it rattles, lists off all her sins, belittles her attempts at redemption, and ends by describing his plans for Clint, whom he has under Mind Control.

""If you fail, if the Tesseract is kept from us, there will be no realm, no barren moon, no crevice where we can't find you. You think you know pain? He will make you long for that so sweet as pain.""
 * Loki's Mind Control in general. Not only do his victims get creepy Blank White Eyes, they retain all their personality traits while under his control, creating a very unsettling effect, since most examples of mind control have the victim acting noticeably out of it. It's like an Uncanny Valley of mind control.
 * Bonus points for the subtle implications that being unconscious undoes the Mind Control, meaning that unless Loki was re-possessing them every morning, anyone under his control was awake the entire time. Which also explains why Clint looked more and more worn down every time we saw him: he hadn't slept for days.
 * Natasha's leg is pinned under some debris... and then Bruce starts to groan and the real panic begins; the mere threat of the Hulk is the only thing that's made her show genuine fear in the film so far, and now she's trapped in an enclosed space while he's on the way. What makes it worse is that Bruce manages to give her an agonized look, powerless to stop what's coming, before he Hulks out practically right next to her. (And also, as par for the course, the transformation looks extremely painful as he tries to fight it.) She manages to free herself before she gets squashed, but what follows is a nightmare chase that ends with her huddled in a dark walkway, very nearly whimpering with pain and shock. This is Black Widow, who beat up three men while tied to a chair and faced down Loki, and she's traumatized.
 * Bruce becoming the Hulk in the above scene is bad enough, but the way he looks at Natasha right before the transformation is complete is absolutely horrifying because he knows what's happening and that there's a huge possibility that she's about to get hurt. And there's nothing he can do because it's too late.
 * The Hulk might be an in universe example for Natasha, the mere prospect that Banner might turn has her pulling her gun on him and she looks terrified. There's a good reason why she says, "Bozhe moi" earlier when Coulson tells her she's getting the "big guy". And he doesn't mean Stark.
 * In the scene mentioned above, it gets worse. At one point, she thinks she's lost the Hulk, so she sneaks through, but then she turns and the Hulk pops up and roars at her, resuming the chase.
 * Hawkeye needs the eye scan of a certain man to open a door that holds a meteorite shard. He gives a hand held scanner to Loki, who proceeds to crash the guy's party, hold him down over a decorative slab in front of the terrified crowd, and - possibly not understanding precisely how the thing works, probably just for kicks - stick the scanner right into the man's eye. We can't directly see the point of impact, but on Hawkeye's end, the scan comes through and the eye is jerking around in death throes.
 * And even if you have no idea who he is, the "challenge accepted" look on his face is unsettling enough. It's even worse if you do.
 * One of Captain America's flashbacks while he's attacking the punch-bag has him recalling a scientist exclaiming he's still alive over his still half frozen body, implying he was conscious for at least some of his defrosting.
 * The very concept of Loki as a villain. Imagine you're fighting an enemy who you know is insane and desperate. You have him locked up, but there's still something not right - it's almost as if he wants you to keep him locked up. Slowly, subtly, he starts messing with your head. Are you still human? Can you be redeemed? He begins to tear at the seams of the only group capable to stop him, getting into your head. The worst part is that, short of manipulating him right back (which is incredibly difficult), you can't stop him from doing it. He's mentally disturbed, nigh-on impossible to kill, and you may not even realize that he's tearing you apart until it's too late.
 * When Tony gets back to Stark Tower and Loki, the god who, is there. Tony's alone, his armor is damaged too badly to use, and the others won't be there for a few minutes yet. He goes in anyway and banters coolly, but the second Loki approaches him with the scepter, just for a second, you see Tony's bravado slip badly, and you realize then just how scared he really is. It just sends shivers up your spine to imagine being in that position.
 * The "cage" Loki is placed in. Manages to hit both claustrophobia (nigh-unbreakable enclosed space) and acrophobia (designed to be dropped 30,000 feet) triggers. There's also a side of Fridge Horror in Bruce Banner's total lack of surprise when Loki mentions the cage was originally designed to contain the Hulk, like he's just resigned to the fact that his "curse" justifies such extreme precautions.
 * threatening Loki. Loki's become quite the hardcore villain since we've last seen him, killing SHIELD agents left and right, mind-controlling people, mind-raping, and doing battle with some pretty tough opponents. And yet that, dear audience, is fear in his eyes, on his face, when  whispers in his ear:
 * threatening Loki. Loki's become quite the hardcore villain since we've last seen him, killing SHIELD agents left and right, mind-controlling people, mind-raping, and doing battle with some pretty tough opponents. And yet that, dear audience, is fear in his eyes, on his face, when  whispers in his ear:


 * The first look we get of Loki. It's this extremely disturbing look in his eyes and a Slasher Smile terrifyingly similar to the profile picture for Nightmare Fuel.