Friedrich (Fritz) Zweigelt (born 13 January 1888 in Hitzendorf near Graz, died 18 September 1964 in Graz) was an Austrian entomologist and phytologist. Zweigelt was one of the most influential and internationally renowned figures in Austrian wine growing between 1921 and 1945. He was Head of State Vine Cultivation during the period of the First Austrian Republic and also acted as Director of the School of Viticulture and Horticulture in Klosterneuburg near Vienna. The grape variety "Blauer Zweigelt" is named after him. Blauer Zweigelt is grown across an area of some 6,400 hectares in Austria, making it by far the most significant red wine grape cultivated in the country. Zweigelt's National Socialist sympathies and activities did not come to the attention of the public for some decades.