| Robert Donald Blue | |
| Order: | 30th |
| Office: | Governor of Iowa |
| Term Start: | January 11, 1945 |
| Term End: | January 13, 1949 |
| Lieutenant: | Kenneth A. Evans |
| Predecessor: | Bourke B. Hickenlooper |
| Successor: | William S. Beardsley |
| Office2: | Lieutenant Governor of Iowa |
| Term Start2: | January 14, 1943 |
| Term End2: | January 11, 1945 |
| Governor2: | Bourke Hickenlooper |
| Predecessor2: | Bourke Hickenlooper |
| Successor2: | Kenneth Evans |
| Order3: | 47th |
| Office3: | Speaker of the Iowa House of Representatives |
| State House3: | Iowa |
| Term Start3: | January 13, 1941 |
| Term End3: | January 14, 1943 |
| Predecessor3: | John R. Irwin |
| Successor3: | Henry W. Burma |
| State House4: | Iowa |
| District4: | 75th |
| Term Start4: | January 14, 1935 |
| Term End4: | January 10, 1943 |
| Predecessor4: | R.E. Lee Aldrich |
| Successor4: | William Tyrrell |
| Birth Date: | September 24, 1898 |
| Birth Place: | Eagle Grove, Iowa |
| Death Place: | Fort Dodge, Iowa |
| Party: | Republican |
| Nationality: | American |
| Alma Mater: | Iowa State University Drake University |
| Profession: | Attorney |
Robert Donald Blue (September 24, 1898 – December 14, 1989) was an American politician, the 30th Governor of Iowa from 1945 to 1949.
Blue attended Capital City Commercial College and Iowa State University. He served in the United States Army during World War I. After the war, he earned a law degree from Drake University Law School in 1922. He practiced law in Eagle Grove and was County Attorney of Wright County, Iowa from 1924 to 1931 and City Attorney of Eagle Grove from 1932 to 1934.
In 1934, Blue was elected to the Iowa House of Representatives. He was reelected in 1936, 1938, 1940, and 1942, and was Speaker of the Iowa House from 1939 to 1943. He was elected the Lieutenant Governor of Iowa in 1942 and then Governor in 1944, winning reelection in 1946.
Blue's policies were unpopular among labor groups (opposed to his bill outlawing the closed shop), farmers (opposed to his tax policies), and teachers (opposed to his cuts in education funding). One of his principal opponents in the legislature, William S. Beardsley, took advantage of Blue's unpopularity and successfully challenged him in the Republican primary in 1948. Blue left public life and returned to his hometown of Eagle Grove. He died of a stroke in Fort Dodge, Iowa on December 14, 1989.
Before his death, the middle school in Eagle Grove, Iowa changed its name to Robert Blue Middle School (RBMS). Mr. Blue was in attendance at the ceremony.