Justus Friedrich Karl Hecker (5 January 1795, in Erfurt – 11 May 1850, in Berlin) was a German physician and medical writer, whose works appear in medical encyclopaedias and journals of the time. He particularly studied disease in relation to human history, including plague, smallpox, infant mortality, dancing mania and the sweating sickness, and is often said to have founded the study of the history of disease.