Eugene Donald Millikin (February 12, 1891 - July 26, 1958) was a United States Senator from Colorado who served as Senate Republican Conference Chairperson from 1947 to 1956. Born in Hamilton, Ohio, Millikin graduated from the law school of the University of Colorado at Boulder in 1913. He was admitted to the bar the same year and commenced practice in Salt Lake City, Utah. He entered politics and served as executive secretary to the Governor form 1915 to 1917. During World War I he enlisted as a private in the Colorado National Guard in 1917, saw action in France and was mustered out as a lieutenant colonel. Millikin resumed the practice of law in Denver, Colorado, and became president of Kinney-Coastal Oil.
Millikin was appointed on December 20, 1941, and subsequently elected on November 3, 1942, as a Republican to the United States Senate to fill the vacancy in the term ending January 3, 1945, caused by the death of Alva B. Adams. He was reelected in 1944 and 1950, and served in all from December 20, 1941 to January 3, 1957. (He was not a candidate for renomination in 1956).
He served as chairman of the U.S. Senate Committee on Finance, the Senate Republican Conference, the U.S. Senate Joint Committee on Internal Revenue Taxation. Millikin died in Denver, and was interred in Fairmount Cemetery.
Preceded by: Alva B. Adams U.S. Senator (Class 3) from Colorado 1941-1957 Succeeded by: John A. Carroll Preceded by: Arthur H. Vandenberg Senate Republican Conference Chairperson 1947-1956 Succeeded by: Leverett Saltonstall Preceded by: Walter F. George Chairman of the U.S. Senate Committee on Finance 1947-1949 Succeeded by: Walter F. George Preceded by: Walter F. George Chairman of the U.S. Senate Committee on Finance 1953-1955 Succeeded by: Harry F. Byrd
