Robert Marion La Follette, Jr. (February 6, 1895 – February 24, 1953) was a United States Senator from Wisconsin from 1925 to 1947, the son of Robert M. La Follette, Sr. and the brother of Philip La Follette.

La Follette Jr. was born in Madison, Wisconsin. He attended the University of Wisconsin, Madison from 1913 to 1917; he served as private secretary to his father between 1919 and 1925.

He was elected as a Republican to the United States Senate on September 29, 1925, to fill the vacancy caused by the death of his father. He was reelected as a Republican in 1928, and as a Progressive in 1934 and 1940. He was an unsuccessful candidate for reelection as a Republican in 1946, losing to Joseph McCarthy.

He was chairman of the Committee on Manufactures in the 71st and 72nd Congresses. La Follette gained national prominence between 1936 and 1940 as chairman of a special Senate investigating committee, commonly called the La Follette Civil Liberties Committee , which exposed the surveillance, physical intimidation and other techniques used by large employers to prevent workers from organizing. He was a foreign aid advisor to the Truman administration; La Follette died in Washington, D.C. of a self-inflicted gunshot wound.