Jackson Pollock
Action painting also called "gestural abstraction", is a style of painting in which paint is spontaneously dribbled, splashed or smeared onto the canvas, rather than being carefully applied. It is generally recognized that Jackson Pollock’s abstract drip paintings, executed from 1947, opened the way to the bolder, gestural techniques that characterize Action painting.
Source: http://www.britannica.com/art/Action-painting