Robert McNutt McElroy (December 28, 1872 - January 15, 1959) was a professor of history at Princeton University from 1898 to 1916.
He was born in Perryville, Kentucky. He married Louise Booker on May 21, 1900. He died in Līhu'e, Hawaii and was buried in Princeton, New Jersey.
He was the first American professor to teach in China on an official professor-exchange program, lecturing there from 1916 to 1917. He became a jingoistic advocate of a strong national defense during World War I, working with the National Security League (NSL).
In April 1918, McElroy accused practically every citizen in the state of Wisconsin of treason. McElroy was addressing some University of Wisconsin Army junior cadets on behalf of the NSL in the rain on the college's campus. The acoustics made it difficult to hear him, and the wet cadets fidgeted throughout his speech. McElroy grew increasingly angry as he spoke, convinced the cadets were ignoring him. Finally McElroy—whether in exasperation or because he truly believed it—accused the students and the university's faculty of treason. But since no one could hear him, there was no response to his statement.