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.

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.

Buchanan died of a heart attack on February 21, 1932, in Richmond, where he was attending a session of the General Assembly.