Sir Peter Bernhard Hirsch FRS (born 16 January 1925) is a figure in British materials science who has made fundamental contributions to the application of transmission electron microscopy to metals. Hirsch attended the Sloane School, Chelsea and St Catharine's College, Cambridge. In 1946 he joined the Crystallography Department of the Cavendish to work for a PhD on work hardening in metals under Lawrence Bragg.