Richard Coulter Drum (May 28, 1825 – October 15, 1909) was an American military officer who was Adjutant General of the United States Army from 1880 to 1889.

At the outbreak of the Mexican–American War in 1846, he enlisted as a private in the 1st Pennsylvania Volunteers, and, the next year, was commissioned a second lieutenant in the 9th Infantry of the Regular Army.

He served as an aide-de-camp for General William S. Harney during his expedition against the Sioux, and participated in the Battle of Ash Hollow.

He was appointed Assistant Adjutant General for the Department of the East, with headquarters in Philadelphia, Pennsylvania from December 27, 1866, to January 6, 1868.

He was again made Assistant Adjutant-General, for the Military Division of the Missouri, in Chicago from November 28, 1873, to May 2, 1878, where he commanded the Federal troops in the Great Railroad Strike of 1877.