'The Wild Bunch'
There had to be a Western on this list, and it had to be "The Wild Bunch." Sam Peckinpah's 1969 movie about a gang of outlaws getting together "for one last score" rewrote cinematic violence. The Motion Picture Production Code, which set strict limits on the types of crime, sex and violence that Hollywood movies could depict, was abandoned in 1968, giving Peckinpah a lot more freedom to make the kind of modern Western he wanted to make [source: Ferrara].
"The Wild Bunch" takes violence to a new level not simply by being more violent, although it certainly does that. Peckinpah makes the carefully orchestrated gun battles and gory deaths key elements of the movie, emphasizing the theme that the life of an outlaw is ultimately empty and can only end in violent death. It isn't a movie with violence in it; "The Wild Bunch" is a movie about violence.
Peckinpah's editing style — fast edits, slow-motion, action shot from multiple angles — inspired a generation of film directors. It's easy to see that Peckinpah himself was influenced by Kurosawa.