Bill Klem, known as the "Old Arbitrator," was a legendary American baseball umpire who worked in the National League for 37 seasons. He was known for his authoritative presence, unwavering integrity, and for pioneering many umpiring techniques, including the use of hand signals. Klem officiated in a record 18 World Series and was among the first umpires to be inducted into the Baseball Hall of Fame in 1953. His dedication to fairness and his famous declaration, "It ain't nothing 'til I call it," have left a permanent mark on the sport of baseball.