George Henry Horn (April 7, 1840 – November 24, 1897) was a U.S. entomologist who specialized in the study of beetles. Born in Philadelphia, Horn attended the University of Pennsylvania, from which he graduated with a degree in medicine in 1861. From 1862 to 1866, he served in the American Civil War as surgeon to the infantry of the California Volunteers, during which time he collected insects extensively in California, Arizona, and New Mexico. He then returned to Philadelphia, where he established a medical practice, specializing in obstetrics, and was elected president of the Entomological Society of Philadelphia, the predecessor of the American Entomological Society. He would remain president of the latter society until his death.