Ralph Owen Brewster was an American politician from Maine. Brewster, a Republican, served as the 54th Governor of Maine from 1925 to 1929, in the U.S. House of Representatives from 1935 to 1941 and in the U.S. Senate from 1941 to 1952. Brewster was a close confidant of Joseph McCarthy of Wisconsin and an antagonist of Howard Hughes, which coupled together resulted in Brewster losing his Senate seat through the unusual defeat of an incumbent Senator in his own primary.