George Stuart Fullerton (1859-1925) was an American philosopher and psychologist. He was the host of the first annual meeting of the American Psychological Association in 1892 at the University of Pennsylvania, and the APA's fifth president, in 1896.
Fullerton was born at Fatehgarh, India; graduated in 1879 from the University of Pennsylvania and in 1884 from Yale Divinity School; and returned to Pennsylvania to be an instructor, adjunct professor, and dean of the department of philosophy, dean of the college, and vice provost of the university. In 1904 he was appointed professor of philosophy at Columbia University, and served as head of the department.
In 1914, while he was exchange professor at the University of Vienna, World War I broke out. Fullerton was imprisoned as a civilian enemy national. He remained imprisoned for four years, until the end of the war, and conditions were so harsh that he returned to the U.S. with his health permanently damaged. (Scottish psychologist Henry J. Watt suffered a similar fate.) Nearly an invalid for the last decade of his life, Fullerton committed suicide at the age of 66.