We know for a fact that people can be very destructive. We can destroy the environment without giving a second thought to it. These movies in this list prove how far people can go both physically and psychologically in torturing other people. Friendly advice, don't watch them all in a movie marathon, try to put some romantic comedies in between.
There are other films whose torture scenes are pretty tough but I personally didn't like on the whole.: "Snuff 102 (2008), Srpski film (2010), Cannibal Holocaust (1980), Salò o le 120 giornate di Sodoma (1975), The Human Centipede (2009)"
The movies were listed according to their IMDb rating.
The storylines were taken from IMDb.