Robert Douglas Walsh (October 10, 1860 – August 15, 1928) was a career officer in the United States Army. An 1883 graduate of the United States Military Academy, he was a veteran of the American Indian Wars, Spanish–American War, Philippine–American War, Pancho Villa Expedition, and World War I. Walsh served until retiring in 1919, and was a recipient of the Army Distinguished Service Medal and French Legion of Honor (Commander).

A native of Alleghany, California, Walsh was raised and educated in Redwood City. He was then appointed to the United States Military Academy at West Point. After his 1883 graduation, he was appointed a second lieutenant of Cavalry. At the start of his career, he served in the western United States during the American Indian Wars and Spanish–American War. Later assignments included several postings to the Philippines during the Philippine–American War. During the Pancho Villa Expedition, Walsh commanded the 8th Cavalry Regiment on the Texas-Mexico border.

During World War I, Walsh commanded two brigades and two U.S. bases in France and received promotion to temporary brigadier general. He retired in 1919, then worked as a New York City-based investment broker. He died in Washington, D.C., on August 15, 1928. Walsh was buried at Arlington National Cemetery.

Robert D. Walsh was born in Alleghany, California on October 14, 1860, a son of Michael Walsh and Johanna Walsh. He was raised and educated in Redwood City, California, and graduated from Redwood City Grammar School, the predecessor of the city's Sequoia High School.

In 1878, Walsh was appointed to the United States Military Academy at West Point. He graduated in 1883 ranked 37th of 52. Walsh's hair was red when he was a young man, causing his classmates to nickname him "Rosy," which they continued to use throughout their careers. Among his classmates were several who also attained general officer rank, including William C. Langfitt, John W. Ruckman, Ira A. Haynes, Chase W. Kennedy, Charles G. Morton, Isaac W. Littell, George H. Cameron, John W. Heard, Harry C. Hale, George W. Read, Samson L. Faison, Omar Bundy, Lawrence D. Tyson, and Clarence R. Edwards. Among his notable classmates who did not become generals was Colonel Thomas Ridgway.

Walsh received his commission as a second lieutenant of Infantry and was assigned to the 22nd Infantry Regiment, but was soon afterwards transferred to the Cavalry and posted to the 4th Cavalry Regiment at Fort Stanton, New Mexico Territory.

From September 1883 to May 1884, Walsh served with the 4th Cavalry at Fort Stanton. He was then assigned to American Indian Wars duty at Fort Huachuca, Arizona Territory and San Carlos Apache Indian Reservation, including an 1885 expedition against the Apache. He remained in Arizona until June 1887. From July 1887 to October 1887, he served at Fort Myer, Virginia, after which he returned to Arizona, where he served at Fort Huachuca and Fort Bowie. In February 1890, he received a brevet promotion to first lieutenant to recognize his heroism during an 1886 engagement against the Apache in the Patagonia Mountains.

In June 1890, Walsh was assigned to Fort Walla Walla, Washington. In March 1891, he was promoted to first lieutenant in the 5th Cavalry Regiment, and in April 1891 he was transferred back to the 4th Cavalry. From July 1891 to September 1893 he served at Jefferson Barracks, Missouri. In September 1893, he was posted to Boise Barracks, Idaho, where he served until July 1899. During the Spanish–American War in 1898, Walsh served as mustering officer for United States Volunteers from Idaho and other nearby states, and in March 1899 he was promoted to captain in the 9th Cavalry Regiment.