Hornig is a surname. Notable people with the surname include:
Donald Hornig (1920–2013), American chemist, explosives expert, teacher and presidential science advisorErnst Hornig (1894-1976), German Bishop of the Evangelical Church of SilesiaHeinz Hornig (born 1937), former German football playerIrina Hornig, skydiver who competed for the SC Dynamo Hoppegarten/ Sportvereinigung (SV) DynamoJoan Hornig, American jewelry designerKároly Hornig (1840–1917), Austrian-Hungarian Cardinal of the Roman Catholic ChurchMady Hornig, MD (born 1957), psychiatrist, associate professor of epidemiology at Columbia University's Mailman School of Public HealthManuel Hornig (born 1982), German football player