Johannes (Hans) Theodor Gustav Ernst Fitting (23 April 1877, Halle an der Saale – 6 July 1970, Köln) was a German plant physiologist.
He studied natural sciences at the universities of Halle and Strasbourg, receiving his doctorate in 1900 as a student of Hermann zu Solms-Laubach.
After graduation, he served as an assistant to Wilhelm Pfeffer at Leipzig, then worked under Hermann Vöchting at the University of Tübingen.
After returning to Germany, he became an associate professor at Strasbourg, then relocated to Halle in 1910, and soon afterwards was named director of the botanical gardens at the colonial institute in Hamburg.
[2] He also made contributions to Eduard Strasburger's "Lehrbuch der Botanik für Hochschulen".