George Henry Falkiner Nuttall FRS (5 July 1862 – 16 December 1937) was an American-British bacteriologist who contributed much to the knowledge of parasites and of insect carriers of diseases. He made significant, innovative discoveries in immunology, about life under aseptic conditions, in blood chemistry, and about diseases transmitted by arthropods, especially ticks. He carried out investigations into the distribution of Anopheline mosquitoes in England in relation to the previous prevalence of malaria there. With William Welch he identified Clostridium perfringens, the organism responsible for causing gangrene. He also demonstrated the importance of intestinal bacteria in digestion and investigated the bactericidal properties of blood.