Gladys Pyle (1890–1989) was a South Dakota politician and the first woman elected to the U.S. Senate without prior appointment. She was also the first female Republican senator, the first female senator from South Dakota, and the first to serve without marrying.

A graduate of Huron College (1911), Pyle taught high school from 1912 to 1918 before entering politics. She became the first woman elected to the South Dakota House of Representatives (1923–1927), later serving as Secretary of State (1927–1931). In 1930, she ran for governor but lost after multiple recounts. She also served on the State Securities Commission (1931–1933) and worked in life insurance.

Pyle and her family were active in the women's suffrage movement, frequently hosting meetings at their home. In 1938, she was elected to the U.S. Senate to complete Peter Norbeck’s term, serving briefly from November 9, 1938, to January 3, 1939.

In 1981, Jeanette Kinyon and Jean Walz began researching Pyle’s life for a biography, gathering materials from interviews, manuscripts, letters, and news reports. This collection represents a selection of their research.