John Aloysius McKeon, nicknamed "Trader Jack," is an American former Major League Baseball manager and front-office executive. In 2003, at age 72, he won a World Series as manager of the Florida Marlins. Two full seasons removed from his previous managing job, McKeon had begun the 2003 season in retirement, but on May 11, he was induced to return to uniform to replace Jeff Torborg as the Marlins' skipper. The team was 16–22 and in next-to-last place in the National League East Division.