The McCormick family of Chicago and Virginia is an American family of Scottish and Scotch-Irish descent that attained prominence and fortune starting with the invention of the McCormick Reaper, a machine that revolutionized agriculture and established the modern grain trade by beginning the mechanization of the harvesting of grain. Through the McCormick Harvesting Machine Company and later, the International Harvester Company and other investments, the McCormicks became one of the wealthiest families in America. The name became ubiquitous in agriculture starting in the 19th century and the press dubbed the McCormicks the "Reaper Kings". Later generations expanded into media and publishing, finance, and real estate. Various family members were well known as civic leaders. They are descended from an influential leader of modern agriculture, inventor Robert McCormick Jr. (1780–1846), and Mary Ann "Polly" Hall of Steeles Tavern, Virginia. The family is Presbyterian.

Robert Hall McCormick was an American inventor who invented numerous devices including a version of the reaper which his eldest son Cyrus McCormick patented in 1834 and became the foundation of the International Harvester Company. Although he lived his life in rural Virginia, he was patriarch of the McCormick family that became influential throughout the world, especially in large cities such as Chicago, Washington, D.C., and New York City.