Stephen Joseph Elledge (born August 7, 1956 in Paris Illinois) is an American geneticist. He is currently the Gregor Mendel Professor of Genetics and Medicine in the Department of Genetics at Harvard Medical School and in the Division of Genetics at the Brigham and Women’s Hospital, and is an Investigator with the Howard Hughes Medical Institute. He earned his B.Sc. in chemistry from the University of Illinois at Urbana–Champaign and his Ph.D. in biology from MIT. His research is focused on the genetic and molecular mechanisms of eukaryotic response to DNA damage. He is a member of the National Academy of Sciences and has been a Howard Hughes Medical Institute (HHMI) investigator since 1993.