Johann Christian Polycarp Erxleben (German: [ˈjoːhan ˈkʁɪsti̯a(ː)n ˈpɔlykaʁp ˈɛʁksˌleːbn̩]; 22 June 1744 – 19 August 1777) was a German naturalist from Quedlinburg.

Erxleben was professor of physics and veterinary medicine at the University of Göttingen. He wrote Anfangsgründe der Naturlehre (1772) and Systema regni animalis (1777). He was founder of the first and oldest academic veterinary school in Germany, the Institute of Veterinary Medicine, in 1771.

He was the son of Dorothea Christiane Erxleben, the first woman in Germany to earn a medical degree.