Unionist John Llewellyn Lewis (February 12, 1880 - June 11, 1969) was president of the United Mine Workers of America from 1920 until his retirement in 1960.

He was born in Lucas, Iowa, the son of an immigrant Welsh coal miner. Lewis began his mining career at age 17. In his early 20s, he left the Lucas mines for a five-year sojourn through the West. After his travels he returned to mining and quickly became a union leader. As a delegate to the UMWA conventions, Lewis attracted the attention of American Federation of Labor President Samuel Gompers, who chose him to be a field representative for the AFL. Lewis used his growing prominence in the AFL to develop a base of support in his home union. He held various positions in the UMWA before becoming president in 1920.

The 1920s were difficult years for the mine workers' organization. Coal companies, using sympathetic governmental and court systems, were particularly successful in preventing union activity in West Virginia and Alabama. In West Virginia, frustrated miners fought back with their 1921 march on Logan County, resulting in the Battle of Blair Mountain. By the end of the decade, the UMW dwindled to fewer than 1,000 dues-paying members in West Virginia. Relief came with the election of Franklin Roosevelt as president. In 1933, the progressive Roosevelt administration secured passage of the National Industrial Recovery Act. Protecting the right of workers to organize and bargain collectively, the NIRA resulted in huge growth in America's unions, including the UMWA. In the late 1930s, Lewis led the drive to establish an organization of industrial unions, the Congress of Industrial Organizations (CIO), for those whom he felt were being neglected by the AFL.

During World War II, Lewis incurred the enmity of President Roosevelt and many Americans by authorizing work stoppages designed to win benefits for miners. Following the war, he secured the first health and retirement plan for UMWA members in return for tacit acceptance of increased mechanization in union coal mines. Through his long career, Lewis received both scorn and admiration for his efforts on behalf of coal miners. His iron control over union organization led to dissension in the union and resulted in the Miners for Democracy movement, which eventually deposed Lewis's successor, Tony Boyle.

John L. Lewis is remembered as an exceptional orator, a tireless worker for his union members, and an effective advocate for all organized labor. He retired as president of the UMWA in 1960 and died at Washington.