Karl Fritsch (24 February 1864 – 17 January 1934) was an Austrian botanist.
In 1900 he moved to the University of Graz as professor of Systematic Botany, where he built up the botanical institute.
In 1910 he was appointed as director of the university's botanical garden, and in 1916 the new institute acquired its own building.
Fritsch's extensive research focussed especially on the flora of Austria.
2801-3600) of the famous exsiccata work Flora exsiccata Austro Hungarica, a museo botanico universitatis vindobonensis edita which was started by Anton Kerner von Marilaun in 1881.