Otha Donner Wearin (January 10, 1903 – April 3, 1990) was a writer and politician. Elected as the youngest member of Franklin D. Roosevelt's first "New Deal" Congress, his political career stalled in 1938 when he gave up his seat at Roosevelt's urging to run for a U.S. Senate seat held by another Democrat, Guy M. Gillette, but primary voters rallied behind Gillette. He became a prolific writer, which led to his election to the Cowboy Hall of Fame.