Boxer Jack is a term used to refer to two of the most famous boxers in history: Muhammad Ali and Max BAER. Muhammad Ali, also known as Cassius Clay, was a three-time world heavyweight champion and one of the most celebrated sports figures of the 20th century. Max BAER was a four-time world heavyweight champion who held the title from 1934 to 1935. Both men were inducted into the International Boxing Hall of Fame.