U.S. professional baseball administrator and first president of the American League of Professional Baseball Clubs (1900–27).

Johnson attended Oberlin and Marietta colleges in Ohio; he also attended law school in Cincinnati but did not finish the course. He became a reporter for the Cincinnati Commercial Gazette in the mid-1890s and later became sports editor. He met many baseball players, owners, and managers, including Charles Comiskey, who in 1894 persuaded him to become president of the Western League. After a year he abandoned his newspaper work and devoted the rest of his life to baseball.

In that period professional baseball was engaged in a “war” between the National League and Johnson's Western League (renamed the American League in 1900). The American League began to move teams into what had been exclusively National League territory, culminating in 1903 with a New York City franchise. In that year the Cincinnati Agreement between the two leagues resolved competition between them. Johnson initiated the annual World Series championship games between the two leagues in 1903 and cleaned up rowdyism at the ballparks to the point that baseball acquired an image conducive to family attendance. Though Johnson helped expose the Black Sox Scandal (q.v.) of 1920, he opposed the appointment of a single commissioner for baseball to replace the earlier three-man commission. His differences with the first commissioner, Kenesaw Mountain Landis, gradually eroded his authority, and he resigned in 1927. He was elected to the Baseball Hall of Fame in 1937.