Ulysses Simpson Grant III (July 4, 1881 – August 29, 1968) was a United States Army officer and planner.

In July and August 1899, both Grant and Douglas MacArthur joined their first summer camp at West Point, and they were especially marked plebes for hazing by upperclassmen since they were the grandson and son, respectively, of well-known men (Ulysses S. Grant and Arthur MacArthur).

From 1918 to 1919, Major Grant served on the staff of General Tasker H. Bliss, the United States representative at the Supreme War Council at Versailles.

In 1919, Grant served on President Woodrow Wilson's commission to negotiate peace in Paris.

By 1927 he was promoted to lieutenant colonel, and was appointed as a co-director of the bicentennial celebration of the birth of George Washington.

Grant expanded the police, instituted plain-clothes patrols, and modernized the force with the addition of motorcycles and automobiles.

In 1936, Grant was the chief of staff of the Second Corps Area at Fort Jay, Governors Island, New York, an army post where his grandfather had stayed prior to his posting to California in 1854 and where his father commanded a department and was division commander until his death in 1912.

While in New York, Grant, his wife, and her siblings and their spouses were present at the bedside of his father-in-law, Elihu Root, when he died in 1937.

From 1941 to mid 1942, he commanded the Engineer Replacement Training Center at Fort Leonard Wood, Missouri.

After his retirement from the army, Grant again served on the National Capital Park and Planning Commission.

Grant's testimony as a Corps of Engineers veteran before Congress in opposition to the Echo Park Dam in Dinosaur National Monument was a key element in the cancellation of the project, and in protection of national park lands against water development projects.

Grant belonged to the Military Order of the Loyal Legion of the United States (MOLLUS), the Sons of Union Veterans of the Civil War (SUVCW) and the Aztec Club of 1847.

After the death of his wife, General Grant remained at his home on the outskirts of Clinton, New York near Hamilton College.