Guy Mark Gillette (February 3, 1879 – March 3, 1973) was an American politician and lawyer who served as a Democratic U.S. Representative (1933–1936) and Senator (1936–1945; 1949–1955) from Iowa.

[4] He nevertheless defeated Roosevelt's choice for the Democratic nomination, Congressman Otha D. Wearin, and was narrowly elected to his first full Senate term.

[3] Nevertheless, he used his chairmanship on a Senate subcommittee to aggressively challenge the Roosevelt administration's failure to prepare for the prospect of a Japanese seizure of the source of the nation's rubber imports by developing synthetic farm-based alternatives.

[3] In April 1943 a confidential analysis by British scholar Isaiah Berlin of the Senate Foreign Relations Committee for the Foreign Office succinctly characterized Gillette: [He] resembles Van Nuys in that he is a typical Mid-Western Senator with a moderately steady Isolationist voting record, although he is not an articulate opponent of the Administration's policy.

A simple, confused, but very honest Presbyterian of considerable character, he views the corn interest, which he represents, with an almost religious devotion.

[7]Like several others who had opposed Roosevelt's efforts to aid the United Kingdom before Pearl Harbor but faced wartime elections, Gillette lost his seat in 1944, to Republican Governor Bourke B.

[11] After resigning from the Surplus Board in May 1945, he became president of the American League for a Free Palestine, serving until the committee's work ended with the establishment of the state of Israel in 1948.

[3] Gillette served until January 3, 1955, after his own bid for re-election was thwarted by U.S. Representative Thomas E. Martin of Iowa City.