Mark Hume McCormack (November 6, 1930 – May 16, 2003) was an American lawyer and sports and celebrity marketing agent. He was the founder and chairman of International Management Group, now IMG, an international management organization that handles the commercial affairs for sports figures and celebrities.
McCormack was the only son of a Chicago publisher named Ned McCormack. A graduate of the College of William and Mary (1951) and Yale Law School, he briefly served in the United States Army. He was an accomplished athlete in his youth and qualified for the 1958 U.S. Open Golf Championship, but he missed the cut. After his Army discharge, he worked for a few years as an attorney at the Cleveland law firm, Arter and Hadden.
In 1960, after realizing the potential of sports in the television age, McCormack signed golfer Arnold Palmer as IMG's first client. IMG and McCormack's clients included sports figures Bjorn Borg, Chris Evert, Pete Sampras, Michael Schumacher, Derek Jeter, Charles Barkley and model Kate Moss. He also handled special projects for Margaret Thatcher, Mikhail Gorbachev and Pope John Paul II. In the nineties, IMG would become Tiger Woods first agency.