Harry Pulliam Cain (January 10, 1906 – March 3, 1979) was an American politician who served as a United States Senator from Washington who served as a Republican from 1946 to 1953. Cain is mainly remembered for his conservative and often highly-controversial views as a member of the Senate and as a friend and supporter of Senator Joseph McCarthy. Prior to his term in the Senate, he had served as the 23rd mayor of Tacoma, Washington. Following his Senate term he was widely recognized as a defender of the civil liberties of individuals accused of being security risks during the Eisenhower Administration and as a community activist and moderate Republican until his death in 1979.