R. John Collier (born August 6, 1938) is an American microbiologist and biochemist.
He is the Maude and Lillian Presley Professor of Microbiology and Immunobiology, Emeritus at Harvard Medical School.
He completed a Master of Science in 1961 and a Doctor of Philosophy in biology at Harvard University in 1964.
At Harvard, Collier served as the Faculty Dean for Graduate Education, Chairman of the Division of Medical Science and Acting Head of the Department of Microbiology and Molecular Genetics.
In 2003, he won the 13th Bristol-Myers Squibb Infectious Disease Research Award.