Thomas Dale Brock (September 10, 1926 – April 4, 2021) was an American microbiologist known for his discovery of hyperthermophiles living in hot springs at Yellowstone National Park. In the late 1960s, Brock discovered high-temperature bacteria living in the Great Fountain region of Yellowstone, and with his colleague Hudson Freeze, they isolated a sample which they named Thermus aquaticus. "Life at High Temperatures", a 1967 article summarizing his research, was published in the journal Science and led to the study of extremophiles, organisms that live in extreme environments. By 1976, T. aquaticus was found useful for artificially amplifying DNA segments. Brock's discoveries led to great progress in biology, contributed to new developments in medicine and agriculture, and helped create t