Operetta films (German: Operettenfilm) are a genre of musical films associated with, but not exclusive to, German language cinema. The genre began in the late 1920s, but its roots stretch back into the tradition of nineteenth century Viennese operettas.
Although some silent films had based their plots on stage operettas, the genre was largely a result of the switch from silent to sound films. The first all-talking operetta was The Desert Song (1929). This operetta had been filmed late in 1928 and was released early in 1929. The 1929 film Melody of the Heart , made by the German studio UFA, is credited as being the first all-talking "operetta film" made in Europe. It had been intended as a silent film, but the dramatic arrival of sound forced its production to be switched. Its combination of music and dancing proved to be a successful formula, and it was followed by many similar films. 
During the 1930s the trend spread to Britain, where a number of Operetta films were made (often in co-productions with German or Austrian studios), France and the United States. Many German émigré film-makers following the Nazi rise to power in 1933 were able to find work in other countries because of their experience in the genre.  In the United States, a popular run of Operetta films were made starring Jeanette MacDonald and Nelson Eddy. In Britain the 1934 Richard Tauber film Blossom Time was a major hit, spawning a number of imitations.
Juliane "Liane" Haid was an Austrian actress and singer. She has often been referred to as Austria's first movie star.
Oscar Nathan Straus was a Viennese composer of operettas, film scores, and songs. He also wrote about 500 cabaret songs, chamber music, and orchestral and choral works. His original name was actually Strauss, but for professional purposes he deliberately omitted the final 's'. He wished not to be associated with the musical Strauss family of Vienna. However, he did follow the advice of Johann Strauss II in 1898 about abandoning the prospective lure of writing waltzes for the more lucrative business of writing for the theatre.
Jan Wiktor Kiepura was a Polish singer and actor.
Oskar Sima was an Austrian actor who is best remembered for appearing in supporting roles in countless comedy films from the 1930s to the 1960s.
Géza von Bolváry was a Hungarian actor, screenwriter, and film director, who worked principally in Germany and Austria.
Marta Eggerth was a Hungarian actress and singer from "The Silver Age of Operetta". Many of the 20th century's most famous operetta composers, including Franz Lehár, Fritz Kreisler, Robert Stolz, Oscar Straus, and Paul Abraham, composed works especially for her.
Willi Forst, born Wilhelm Anton Frohs was an Austrian actor, screenwriter, film director, film producer and singer. As a debonair actor he was a darling of the German-speaking film audiences, as a director, one of the most significant makers of the Viennese period musical melodramas and comedies of the 1930s known as Wiener Filme. From the mid-1930s he also recorded many records, largely of sentimental Viennese songs, for the Odeon Records label owned by Carl Lindström AG.
Paul Otto Schlesinger was a German film actor and director. Born in Berlin, he began a qualification as a retail merchant and made his actor's debut at the age of 17. Otto worked at Theaters in Halle, Wiesbaden and Hanover before he returned to Berlin about 1906.
Walter Reisch was an Austrian-born director and screenwriter. He also wrote lyrics to several songs featured in his films, one popular title is "Flieger, grüß mir die Sonne". He was married to the dancer and actress Poldi Dur and was the cousin of Georg Kreisler.
Willy Schmidt-Gentner was one of the most successful German composers of film music in the history of German-language cinema. He moved to Vienna in 1933. At his most productive, he scored up to 10 films a year, including numerous classics and masterpieces of the German and Austrian cinema.
Wiener Film is an Austrian film genre, consisting of a combination of comedy, romance and melodrama in a historical setting, mostly, and typically, the Vienna of the late 19th and early 20th centuries. The Wiener Film genre was in production between the 1920s and the 1950s, with the 1930s as its high period.
Harry Hardt was an Austrian actor. The son of a military officer, he initially planned a military career for himself, studying at a military academy and serving during World War I. He later turned to acting, having a long career both in films and on television.
Paul Hörbiger was an Austrian theatre and film actor.
Otto Wallburg was a German actor and Kabarett performer. He was a prolific film actor during the late silent and early sound era.
Hans May was an Austrian-born composer who went into exile in Britain in 1936 after the Nazis came to power in his homeland, being of Jewish descent.
Georg Alexander was a German film actor who was a prolific presence in German cinema. He also directed a number of films during the silent era.
Anton Pointner was an Austrian stage and film actor. Pointner's career began on the stages of Austria and performed in both silent and sound films in his native Austria, as well as in Germany and the United States.
Alfred Neugebauer was an Austrian film actor.
Carl Drews was a German cinematographer.