4. John Harvey Kellogg (can also refer to the co-founder of the Kellogg Company)

John Harvey Kellogg was an American physician and health reformer in the late 19th and early 20th centuries, known for promoting vegetarianism and plant-based diets. He co-founded the Kellogg Company, famous for its breakfast cereals, to provide healthier food options. Kellogg believed in the importance of diet for physical and mental well-being, advocating for exercise and hygiene. He also invented cornflakes as a healthy, ready-to-eat breakfast item. His ideas and products significantly influenced modern eating habits and the breakfast food industry.