Dr. Charles Reynolds, Dr. Barry Marshall

Dr. Charles Reynolds names another doctor with a very cool story. Dr. Barry Marshall became convinced that peptic ulcers and gastric cancer were both caused by a specific sort of bacterium. He eventually proved his hypothesis by drinking a culture filled with ulcer causing bacteria and giving himself an ulcer. But there's actually a lot of debate about whether or not the medical community was wrong to be as skeptical about his ideas as they were.