Have you ever had a truly disturbing and/or horrifying dream?

Inspired by this question.

I once dreamt that I was walking through some fields to an abandoned schoolhouse. When I walked inside there were at least 20 children, all sitting at their desks, bloody and battered. I got a closer look and noticed that all of their hands were nailed together. One child’s hand was placed on top of another child’s hand sitting next to them with a huge nail lodged through the two. As soon as they all noticed I was in the room, they immediately straightened up in their chairs, cowered when I came near and started calling me “master”. (Shudders)
The worst part is, I remember how powerful I felt and that I actually enjoyed the fact that they were afraid of me. I refused to help them. I just let them suffer. I remember getting pissed when they tried to escape too. I don’t know why I reacted that way. I think that’s what shook me the most when I woke up. The fact that I didn’t do anything about it.

Several years ago, I had four tiny consecutive dreams in a row the same night.
1) I was sitting in a car in an empty parking lot with my mother. She handed me a package and asked me to hand it to someone outside the vehicle. I got out of the car and suddenly this strong force began pushing me toward the darkness in the distance. I couldn’t stop it.
2) Then suddenly I was lying on the ground in my living room and I couldn’t move. I was completely paralyzed. A black cat with bright yellow eyes was sitting by my feet staring at me and out of the corner of my eye I could see another cat sitting by my shoulder. This motherfucker was eating my shoulder and I could actually feel little sharp pains every time he took a bite.
3) Then I was at a friend’s house. She invited me inside. She looked at me and the smile from her face disappeared. She looked at my arms. I peered down at my sweatshirt sleeves and blood was slowly soaking through them. I quickly rolled them up to reveal what was underneath and both of my wrists were slashed.
4) Lastly, I found myself back at my old house. I glanced at my wrists and they were fine. As I ran my fingers through my hair, huge clumps fell out into my hands. I walked to the mirror and I was balding. I had huge patches of hair missing. Suddenly, I could hear my mother on the front porch getting ready to walk inside the house. I panicked and hid in a corner.

Then I woke up. I was terrified. Both of those dreams deeply bothered me.

Have you ever had a dream like this that shook you to the core?