Barry James Marshall, AC, FRACP, FRS, FAA, DSc is an Australian physician, Nobel Prize laureate in Physiology or Medicine, and Professor of Clinical Microbiology at the University of Western Australia. Marshall and Robin Warren showed that the bacterium Helicobacter pylori is the cause of most peptic ulcers, reversing decades of medical doctrine holding that ulcers were caused by stress, spicy foods, and too much acid. This discovery has allowed for a breakthrough in understanding a causative link between Helicobacter pylori infection and stomach cancer. 

September 30th, 1951 in Kalgoorlie (Age 73)