Elizabeth MacGregor Hardy (July 31, 1915 – June 26, 2008) was a North American chemist who discovered the Cope rearrangement while working in Arthur C. Cope's research group at Bryn Mawr College. The rearrangement drew upon the electronic models of Edward D. Hughes and Christopher Kelk Ingold, but also the non-electronic work of Rainer Ludwig Claisen and Ernst Tietze.