Liesl Karlstadt, born December 12, 1892, as Elisabeth Wellano in Munich, at first worked as a salesclerk and as a baker. At the age of 20, she became a singer and dancer for Adalbert Meier's musical comedy group and performed as an actress on stage in plays such as "Kabale und Liebe" and "Die Kameliendame".

In 1911, Karlstadt met Karl Valentin at the "Frankfurter Hof". This meeting marked the beginning of a prolific and successful collaboration. The duo of Valentin and Karlstadt ranks among the most famous and groundbreaking comedy duos of the 20th century. During their 25-year long collaboration, Valentin and Karlstadt did around 400 sketches, many of them written by Liesl Karlstadt herself. Besides their success on stage, Valentin and Karlstadt also became pioneers of the cinema as they experimented with the new medium as early as 1912.

Karlstadt appeared in numerous comedic silent movies during the 1920s. In 1930, she decided to attend professional actor's training. Nevertheless, she did not manage to escape Valentin's shadow. Moreover, their relationship in private was not always the best. After the wayward Valentin had lost Karlstadt's entire fortune through a bad investment, she attempted suicide. After her recovery, Karlstadt played in a couple of successful films such as "Der Bittsteller" or "Beim Rechtsanwalt" (both 1936) – again alongside Karl Valentin.

Karlstadt's popularity continued also after Valentin's death in 1948, but in the following years she was more successful in more serious roles at the Munich Residenztheater and the Kammerspiele. At the Bayerischer Rundfunk she got her own show with "Familie Brandl". On the big screen she mainly appeared in supporting roles. To her most famous movies of this time belong "Fanfaren der Ehe" (1953), "Die Trapp-Familie" ("The Trapp Family", 1956) and the satire "Wir Wunderkinder" ("Aren't We Wonderful?", 1958).

On 27 July 1960 Liesl Karlstadt died of a stroke in Garmisch-Partenkirchen. The "Valentin Karlstadt Museum" in Munich is dedicated to her and Karl Valentin.