Catherine "Cathy" J. Murphy (born 1964) is an American chemist and materials scientist, and is the Larry Faulkner Professor of Chemistry at the University of Illinois at Urbana-Champaign (UIUC). The first woman to serve as the Head of the Department of Chemistry at UIUC, Murphy is known for her work on nanomaterials, specifically the seed-mediated synthesis of gold nanorods of controlled aspect ratio. She is a member of the American Association for the Advancement of Science, National Academy of Sciences, and the American Academy of Arts and Sciences in 2019.