Claire Waldoff (21 October 1884 – 22 January 1957), born Clara Wortmann, was a German singer. She was a famous kabarett singer and entertainer in Berlin during the 1910s to the 1930s, chiefly known for performing ironic songs in the Berlin dialect and with lesbian undertones and themes. Wortmann was born the eleventh child of sixteen in Gelsenkirchen, Westphalia, where her parents owned a tavern. After completing Gymnasium school in Hanover, she trained as an actress and chose as her pseudonym Claire Waldoff. In 1903, she got her first theatre jobs in Bad Pyrmont and in Kattowitz (Katowice), Silesia. In 1906, Waldoff went to Berlin, where she performed at the Figaro-Theater on Kurfürstendamm. In 1907, she also began a working as a cabaret singer. She made her breakthrough when Rudolf Nelson gave her a job at the Roland von Berlin theatre near Potsdamer Platz. Initially planning to perform antimilitarist pieces by Paul Scheerbart in a men's suit, Waldoff had greater success with less offensive catchy songs written by Walter Kollo. During the next several years in German cabaret, she sang at Chat Noir on Friedrichstraße and at the Linden-Cabaret on Unter den Linden. During World War I, when many cabarets were closed, she performed at the Theater am Nollendorfplatz and in Königsberg. Waldoff's success reached its peak in the Weimar Republic era of the 1920s. She was known for singing her songs in distinctive Berliner slang, attired in a shirt with a tie and the fashionable crop hairstyle, cursing and smoking cigarettes on stage. From 1924 she performed at the two great Berlin varieté theatres, Scala and Wintergarten, sang together with young Marlene Dietrich, and had her songs played on the radio as well as released on record. Her repertoire included around 300 original songs. Waldoff lived together with her significant other Olga "Olly" von Roeder (12 June 1886 – 11 July 1963) until her death. The couple lived happily in Berlin during the 1920s. Part of the queer scene, they associated with celebrities like Anita Berber in the milieu around Damenklub Pyramide near Nollendorfplatz.