Cornelius McGillicuddy III (born October 29, 1940 in Philadelphia, Pennsylvania), known as Connie Mack for short, is a former Republican member of the United States House of Representatives from 1983 to 1989 and of the United States Senate from 1989 to 2001, all from Florida. He served as chairman of the Senate Republican Conference, 1997-2001.

He is the grandson of Connie Mack, the manager and owner of baseball's Philadelphia Athletics, and member of the Baseball Hall of Fame. His son, Connie Mack IV, a former Florida State Senator, was elected to his father's old U.S. House seat in 2004.