Gregory S. Girolami (born October 16, 1956) is the William H. and Janet G. Lycan Professor of Chemistry at the University of Illinois Urbana-Champaign. His research focuses on the synthesis, properties, and reactivity of new inorganic, organometallic, and solid state species. Girolami has been elected a fellow of the American Association for the Advancement of Science, the Royal Society of Chemistry, and the American Chemical Society.