Roger John Williams (August 14, 1893 – February 20, 1988), was an American biochemist. He is known for is work on vitamins and human nutrition. He had leading roles in the discovery of folic acid, pantothenic acid, vitamin B6, lipoic acid, and avidin. He was elected to the National Academy of Sciences in 1946, and served as the president of the American Chemical Society in 1957. In his later career he spent time writing for a popular audience on the importance of nutrition.