John Roy Campbell (June 14, 1933 – November 17, 2018) was an American dairy scientist and university administrator who was a professor of dairy science at the University of Missouri from 1960 to 1977, was professor, Associate Dean and Dean of Agriculture at the University of Illinois from 1977 to 1988, and was professor at Oklahoma State University from 1988 to 1993, serving as University President from 1988 to 1993.