As a kid, I used to be quite sensitive in the matter of what I saw or heard or read, but now I'm a little bit more realistic and understand that all things described in books or shown in movies are just stuff that once came to someone's mind, so they literally may mean nothing to me. But even despite that, there're still a few things I'd rather forget and never come back to.
Ernest Thompson Seton's "Lobo the king of Currumpaw" shook a ***t out of me as a child. I love animals, and any act of violence towards them in literature or cinema or real life usually leaves me with nothing but an urge to cry and kill. In Lobo, they told me about a violent death of a she-wolf, and even though I realize it could be not that scary and awful and all, I don't feel like rereading the stuff.
The same thing happened when I accidentally watched a movie on telly, don't even remember its name, and it was about a guy who suffered from a lab experiment and became invisible. He tried to escape, and there was a dog - it was barking at him, as it was able to feel his presence, and the guy just broke its neck or something. I hate cinematographers for that.
And literally the same happened when I watched John Wick for the first time. His little bigle puppy's murder in the beginning is still the scene I avoid when watching the movie on TV.
I tried to recall anything connected to human death that left me scarred... and couldn't. The only thing that probably counts is Harry Potter movies, simply because my favorite characters suffered and died throughout the whole series, also because of the true personalities "reveal show" at the end that left a strong pain inside my chest.
Any movies where people die in a very inelegant or even stupid, bloody way don't really impress me anymore as I went far beyond my love towards humanity, to the next stage of it - sincere hatred. And books... well, books are something that I choose carefully before bying and reading, so I rarely stumble upon stuff that I don't like. Okay, there was a book where a little boy and his friend murdered a bunch of sparrow hatchlings in such a ruthless way, it left me literally frozen. And not that I had a choice of not reading it, 'cause it was included in my school program. Yeah.