Boris Magasanik (December 19, 1919 – December 25, 2013) was a microbiologist and biochemist who was the Jacques Monod Professor Emeritus of Microbiology in the Department of Biology at the Massachusetts Institute of Technology. After moving from Harvard Medical School in 1960, Magasanik spent the rest of his research career at MIT, including an influential decade as the head of the Department of Biology from 1967–77. Magasanik's research interests focused on gene regulation, including study of nitrogen metabolic regulation in bacteria, catabolite repression, and intracellular signaling via two-component systems. Magasanik retired in 1990 and died in 2013.