Robert Joseph Maurer (1913-1995) was an American physicist.
Maurer received his Ph.D. from the University of Rochester in 1939 and was one of Lee DuBridge's last students before DuBridge left to head the Radiation Laboratory at MIT. During World War II, Maurer researched the possibility of using semiconductors as radar detectors.
In 1944, he was asked to join the Metallurgical Laboratory at the University of Chicago. At Chicago, he studied the effects of the high level of radiation flux in the plutonium reactors at Hanford. He signed the Szilard Petition, which urged President Truman to demonstrate the bomb instead of dropping it on a Japanese city.
Maurer was a professor of physics for many years at the University of Illinois, and served as the first director of the University's Materials Research Laboratory. He also headed the physics division at the Naval Research Laboratory and taught at MIT, the University of Pennsylvania, and Carnegie Institute of Technology.