Diana Gabaldon's Outlander series is a goldmine for Nightmare Fuel. It's definitely a change of some sort from the average quasi-fluffy historical romance.
- A particularly brutal rape scene in the first book. Oh God, Jamie's fingers.
- The Shown Their Work-quality medical scenes showcasing the best of 18th century supplies and techniques, especially the aftermath of someone in The Fiery Cross getting basically lynched, and the graphic descriptions of the damage already done, even though the main characters manage to keep him from dying outright.
- In another scene in the same novel, there's another gloriously, gloriously detailed description of a man left catatonic from a stroke lying on the floor of his house, literally rotting because his wife, who he'd been beating, refused to help him.
- The entire premise can be Fridge Horror. Particularly with the thought in mind that not everyone gets through the stone circles... intact, as it were. And even if you do get through fine, you're lost, disoriented, broke, and in an entirely different time period. One you almost certainly didn't come fully prepared for. Unless you're very, very lucky.
- The mere experience of going through the stones is shown to be quite traumatic for adults. Mandy seems to have some memory of it, despite being less than a year old at the time. Jem definitely remembers.
- In one of the Lord John side-novels, there's mention of how the main character had been raped as a teenager. And how never knowing the identity of his rapist, he had to carry on functioning with no way to be sure if it had been just bad luck that he'd been there... or if the rapist was someone he knew, someone he interacts with on a daily basis. And not being able to tell anyone. It's by no means the most overtly disturbing mention of rape in Gabaldon's books, but it made me shudder.
- After an outburst from Jem, Brianna realizes that Lionel Menzies suspects Rob had taken Jem to rape the boy. She doesn't entirely dissuade Menzies of this notion, though Menzies later finds out about the time travel element. Under the circumstances, one wouldn't be surprised if Menzie's initial assumption was shared by others as well.
- Brianna joining her parents in the past could be considered this, since Claire feels partially responsible for any harm that comes to Brianna in the past. If Brianna had died in childbirth or of some other preventable disease, I doubt Claire would ever forgive herself.
- The Moorwen's "roar." It's like three sounds in one. Imagine the low rumble of massive shifting rocks, a bit of a lion's guttural growl in the middle, topped off with a higher pitched metallic screech. It's not until halfway through the film that we actually see the beast, so all we get is this unnerving sound and the ominous lights preceding an attack.