Howard Percy "Bob" Robertson (January 27, 1903 – August 26, 1961) was an American mathematician and physicist known for contributions related to physical cosmology and the uncertainty principle. He was Professor of Mathematical Physics at the California Institute of Technology and Princeton University.

Robertson made important contributions to the mathematics of quantum mechanics, general relativity and differential geometry. Applying relativity to cosmology, he independently developed the concept of an expanding universe. His name is most often associated with the Poynting–Robertson effect, the process by which solar radiation causes a dust mote orbiting a star to lose angular momentum, which he also described in terms of general relativity.

During World War II, Robertson served with the National Defense Research Committee (NDRC) and the Office of Scientific Research and Development (OSRD). He served as Technical Consultant to the Secretary of War, the OSRD Liaison Officer in London, and the Chief of the Scientific Intelligence Advisory Section at Supreme Headquarters Allied Expeditionary Force.

After the war Robertson was director of the Weapons Systems Evaluation Group in the Office of the Secretary of Defense from 1950 to 1952, chairman of the Robertson Panel on UFOs in 1953 and Scientific Advisor to the NATO Supreme Allied Commander Europe (SACEUR) in 1954 and 1955. He was Chairman of the Defense Science Board from 1956 to 1961, and a member of the President's Science Advisory Committee (PSAC) from 1957 to 1961.

A crater on the far side of the moon is named in his honor.