Threads was a made-for-TV production by BBC back in the 80's (we didn't have cable back in the day!) I watched with my brother one Sunday afternoon about a nuclear attack on England. Society collapses, and the children born to survivors can't even speak English. The movie ends with the daughter of a survivor giving birth to a dead, deformed baby. The worst part is a melting cat in the street during the attack, and the government officials suffocate in a bomb shelter.
It's not available on DVD in the US, but you can see most of it in clips on youtube.
I Spit On Your Grave takes the cake, eats it, regurgitates it, eats it again, digests it, eats it again and continues till there is nothing left at all but a burp
If it hasn't been mentioned earlier "Man Bites Dog". Violence against women just for the shock value.
Totally abhorrent and had to turn off after 15 min.
I don't know if was mentioned before but "Irreversable" was not only disturbing, I found it offensive, and hated it. There is a rape scene that seems to go on for 10min. and after that is done we get to watch her get beat up for 5min.
I have a tendancy to see a lot of films that are disturbing to others, some of them mentioned in the thread, but this I think tops them all.
This made such an impact on me when it came out; it played a huge role in changing how I see the world and my political leanings. Alan Rickman is amazing in this role. Produced by Amnesty International, it is simply a political prisoner and her questioner.