Julius Bittner (born Vienna, 9 April 1874; died Vienna, 9 January 1939) was an Austrian composer.
The son of a judge, Bittner also initially pursued a career in law. Until 1920 he was a judge in Wolkersdorf im Weinviertel, in Lower Austria. From 1920 to 1922 or 1923 he was an official in the Austrian Department of Justice.
In addition, Julius Bittner became one of the best known and most performed Austrian opera composers in the first half of the 20th Century. Many of his operas deal with Austrian-Alpine themes. He usually wrote his own libretti. After the Second World War, however, as a typical representative of late Romantic opera in the tradition of Richard Wagner, he was gradually forgotten. Critics gave him the somewhat derogatory nickname "the Anzengruber of the opera"; in importance he is comparable to his better known contemporary Wilhelm Kienzl.
Bittner was married to the alto Emilie Werner. As a leading member of Vienna's judiciary and close friend of Gustav Mahler, he assessed Mahler’s estate for probate after his death. He later won the Mahler Prize in 1915. He composed many operas, two symphonies and many songs and was helped and promoted by Mahler and Bruno Walter. He was also a close friend of Erich Wolfgang Korngold and Franz Schmidt. He was for a while editor of the Austrian music journal Der Merker and wrote music criticism for it and other newspapers. He was so influential that he was able to arrange Arnold Schoenberg's release from active military service in the First World War.
He received numerous awards and honors and became a member of the Prussian Academy of Arts in Berlin in 1925. In 1964, the archive containing almost all of his works (autograph sketches, text books, scores and piano reductions) was taken over by the Vienna City Library.