John William Harris (born March 14, 1950) is an American experimental high energy nuclear physicist and D. Allan Bromley Professor of Physics at Yale University.

His research interests are focused on understanding high energy density QCD and the quark–gluon plasma created in relativistic collisions of heavy ions.

Dr. Harris collaborated on the original proposal to initiate a high energy heavy ion program at CERN in Geneva, Switzerland, has been actively involved in the CERN heavy ion program and was the founding spokesperson for the STAR collaboration at RHIC at Brookhaven National Laboratory in the U.S. After obtaining a Bachelor of Science, with Distinction, from the University of Washington, John Harris started his career at the Stony Brook University (then known as State University of New York at Stony Brook), where he completed his Ph.D. in experimental nuclear physics in 1978.

After working as a senior guest scientist at the Gesellschaft für Schwerionenforschung in Darmstadt, Germany, from 1980 to 1984, he returned to LBNL in 1984 and was appointed divisional fellow in the Nuclear Science Division.

[4] In 1996, Harris joined the faculty of Yale University in New Haven, Connecticut, as a tenured professor of physics.