Patrick A. Nash (March 2, 1863 – October 6, 1943) was a political boss in the early and mid-twentieth century in Chicago, which is in Cook County, Illinois, United States. He was in large part responsible for consolidating elements of the Cook County Democratic Party into a political machine. He evolved from a local sewage contractor to a political boss by carefully selecting his political allies. His prominence stems from the death of Anton Cermak and his political career is intertwined with that of Edward Joseph Kelly. The success of this machine was attributed to its decision to be more inclusive than its predecessors. This meant that Nash had success at dealing with a variety of politicians such as William L. Dawson.