Oh lord, this is a tough one for me because I've had a few just awful reoccurring ones. There's one where I'm home with my family (my mom and little sister), guys in ski masks break in, I try to fight them off but can't, they drag me off, and I wake up just as they're getting ready to rape me. I have that one every few years or so. More recently, I keep having dreams where my teeth and finger/toe nails start falling out. Which probably doesn't sound as horrific, but it's always insanely realistic and each time I wake up I find myself checking for all my parts. Also, there was a real recent one where I was watching a bunch of horrific medical experiments/torture. Last one was watching myself, with my legs already cut off, getting strapped down to this old-time asylum gurney, where they injected me with something that made my brains boil up out through my eyes. Simultaneously they pushed my hand into a hamburger grinder.
I'm incredibly thankful that most nights I don't dream at all. Not sure if I can even remember any good dreams, it's always effed up stuff like this. Even the seemingly good ones (IE, going back to a childhood favorite movie theater) end with somebody getting lost or something.
_________________
Inside every cynical person, there is a disappointed idealist. --George Carlin