| State Senate: | Virginia |
| District: | 15th |
| Term Start: | January 9, 1924 |
| Term End: | February 21, 1932 |
| Preceded: | John J. Miller |
| Succeeded: | Burt L. Dickinson |
| Order1: | 21st |
| Office1: | Lieutenant Governor of Virginia |
| Term Start1: | February 1, 1918 |
| Term End1: | February 1, 1922 |
| Governor1: | Westmoreland Davis |
| Predecessor1: | James Taylor Ellyson |
| Successor1: | Junius Edgar West |
| State Senate2: | Virginia |
| District2: | 1st |
| Term Start2: | January 14, 1914 |
| Term End2: | January 12, 1916 |
| Preceded2: | David C. Cummings Jr. |
| Succeeded2: | John P. Buchanan |
| Term Start3: | December 6, 1893 |
| Term End3: | December 1, 1897 |
| Predecessor3: | E. L. Roberts |
| Successor3: | Charles W. Steele |
| Birth Date: | October 4, 1857 |
| Birth Place: | Smyth County, Virginia, U.S. |
| Death Place: | Richmond, Virginia, U.S. |
| Spouse: | Eleanor Fairman Sheffey |
| Alma Mater: | University of Virginia |
| Party: | Democrat |
Benjamin Franklin Buchanan (October 4, 1857 – February 21, 1932) was an American lawyer and politician who served as the 21st Lieutenant Governor of Virginia from 1918 to 1922.
Buchanan was born October 4, 1857, in Smyth County, Virginia, and graduated from the University of Virginia in 1880. He also received an LL.B. from the University of Virginia in 1884.
Buchanan practiced law in Marion and Abingdon. He also served as general counsel to the office of the United States comptroller of the currency from 1915 to 1921. He served several terms in the Senate of Virginia representing Smyth and Washington Counties, where he became one of the General Assembly's foremost authorities on taxation.
In 1917 Buchanan, a Democrat, won election as lieutenant governor of Virginia. He served from February 1, 1918, to February 1, 1922.
Buchanan died of a heart attack on February 21, 1932, in Richmond, where he was attending a session of the General Assembly. He was buried in Round Hill Cemetery in Marion. In 1934 the General Assembly designated the road that became state highway 16 in Smyth County the B. F. Buchanan Highway.
On March 2, 1887, Buchanan married Eleanor Fairman Sheffey. They had four sons and three daughters, including John Preston Buchanan, who succeeded Buchanan in the Senate.