Otto Antonius (21 May 1885 in Vienna – 9 April 1945 in Vienna) was director of the Tiergarten Schönbrunn in Vienna, zoologist, palaeontologist and co-founder of the modern zoological biology.
Otto Antonius was the eldest of five children. His father was Protestant minister a native of Transylvania. Otto was named after the German chancellor Otto von Bismarck.
He attended classical grammar school in Vienna and studied in particular natural sciences, zoology and palaeontology at the University of Vienna. During his years of study, Antonius joined a nationalist fraternity, named “Silesia” which strove for a Pan-German solution. His father and three of his brothers were also members of this student organisation.
In 1910 he received his PhD and started to work for Professor Othenio Abel as scientific assistant at the chair of palaeobiology. Until 1918 he served in World War I as lieutenant and liaison officer. He received several medals: the Eisernes Kreuz, the Eiserner Halbmond and the Silberne Tapferkeitsmedaille.
In 1919 he resumed his scientific work as assistant professor. The same year he received his habilitation from the University of Vienna, in 1921 from the University of Agriculture.
In 1922 he married Margarethe von Tunner, they had two daughters.
On 1 December 1923 he started his regular duty at the Schönbrunn Zoo. Four months later he was named scientific director and eventually became palaeontologist and expert for zoological science on domestic animals. On 1 December 1925 he became the only director with full responsibilities.
In March 1934 Antonius was officially dismissed, due to accusations of being an active member of the NSDAP which was illegal in Austria. Antonius denied this allegation and sued successfully. At the fourth of January 1937 he was reinstalled as director.