Ernst Franz August Stowasser, born January 7, 1894, died December 2, 1929, Father of Friedensreich Hundertwasser
Little is known about Ernst Stowasser, which may be explained by Hundertwasser's statement in an interview with Georg Markus: "My father died when I was one year old, probably as a result of appendicitis. I only remember him as a photograph. My mother never spoke of him very much and when she did, she didn't speak of him particularly well. She was probably superior to him in everything and so, even when he was still around, everything weighed on her shoulders. In the late 1920s, my father was one of hundreds of thousands of unemployed people, while my mother, as an employee of the Creditanstalt, raised the money we could live on fairly and poorly."
(Between the HJ and the Jewish star, see https://hundertwasser.com/texte/between_hitler_youth_and_the_star_of_david_excerpt)
The cause of death was peritonitis, presumably as a result of appendicitis or a ruptured appendix.
Ernst Stowasser served in the First World War and in the same interview Hundertwasser mentions his father's medals for bravery, which he presented to the SS henchmen, so that although they twice announced the evacuation of the apartment, they did not carry out the collection.