Haasis (born 7 January 1942) is a German historian, author, and broadcaster.
He is particularly known for his biographies of Georg Elser who attempted to assassinate Adolf Hitler in 1939; Reinhard Heydrich who was one of the main architects of the Holocaust; and Joseph Süß Oppenheimer who was executed in 1738 and in 1940 was the subject of a notorious Nazi anti-semitic propaganda film, Jud Süß.
Haasis was born in Mühlacker, a town in the Swabia region of Germany, and has written two novels in Swabian dialect as well as a collection of poetry.
He is the recipient of the Thaddäus Troll Literature Prize, the Schubart Literature Prize, and the Civis Media Prize.