William Frederick Lemke was an American politician who represented North Dakota in the United States House of Representatives as a member of the Republican Party. He was also the Union Party's presidential candidate in the 1936 presidential election.

The Union Party was a short-lived political party in the United States, formed in 1936 by a coalition of radio priest Father Charles Coughlin, old-age pension advocate Francis Townsend, and Gerald L. K. Smith, who had taken control of Huey Long's Share Our Wealth (SOW) movement after Long's assassination in 1935. Each of those people hoped to channel their wide followings into support for the Union Party, which proposed a populist alternative to the New Deal reforms of Franklin D. Roosevelt during the Great Depression.