Harry Simmons (September 29, 1907 – January 14, 1998) was an American professional baseball executive, writer and historian. He worked in Minor League Baseball for the International League from 1946 until 1966, first in New York City then in Montreal. He then worked in Major League Baseball for the Office of the Commissioner of Baseball until his retirement in 1982. Simmons was nicknamed "Mr. Baseball" and is an inductee of the Canadian Baseball Hall of Fame.