Raymond Lee Orbach is an American physicist and administrator. He served as Under Secretary for Science in the United States Department of Energy from 2006 until 2009, when he was replaced by Steve Koonin.

Orbach received a Bachelor of Science degree in Physics from the California Institute of Technology in 1956 and a Ph.D. degree in Physics from the University of California, Berkeley, in 1960. Orbach began his academic career as a postdoctoral fellow at Oxford University in 1960 and became an assistant professor of applied physics at Harvard University in 1961. He joined the faculty of the University of California, Los Angeles (UCLA) two years later as an associate professor, and became a full professor in 1966.

Orbach's research in theoretical and experimental physics has resulted in the publication of more than 240 scientific articles, and he is a fellow of the American Physical Society and the American Association for the Advancement of Science.