Fred (Friedrich) Neufeld (17 February 1869 in Danzig – 18 April 1945 in Berlin) was a physician and bacteriologist who discovered the pneumococcal types. This discovery led Fred Griffith to show that one pneumococcal type could be transformed into another (Griffith's experiment). Subsequently, Oswald Avery demonstrated that the transforming substance was DNA. All modern molecular biology has evolved from this work.