Karl Theodor Paul Polykarpus Axenfeld (24 June 1867 – 29 July 1930) was a German ophthalmologist born in Smyrna (İzmir) in the Ottoman Empire to a German minister, who was a Jewish convert to Christianity and served as missionary in Asia Minor.
In 1896 he became an assistant to Wilhelm Uhthoff (1853–1927) at Breslau, and during the following year, was appointed director of the university eye clinic in Rostock.
He published numerous articles on glaucoma, retinal disorders, trachoma and other eye maladies.
In 1909 he was awarded the Graefe Medal by the German Ophthalmological Society for his research of sympathetic ophthalmia.
With Otto von Schjerning (1853-1921), he collaborated on the Handbuch der ärztlichen Erfahrungen im Weltkriege.