Mary Losseff (also Mara Loseff); (13 March 1907, Vladivostok – 3 July 1972, London) was a Russian-born British singer and film actress.
She was the muse for his 1934 operetta Der singende Traum and his three songs titled An eine schöne Frau, and she also starred opposite him in numerous productions.
This period is described by her then-lover, the pianist and composer Peter Kreuder, in his book Nur Puppen habe keine Tränen.
Tauber was in the audience at the Nelson Review and fell in love with Mary, and her voice, at first sight; he felt that she was the singer for whom he had long been searching to star in his planned operetta Der singende Traum.
Initially through his influence, she secured major roles in several productions, including Paul Abraham's Viktoria und ihr Husar, Karl Millöcker's Die Dubarry, Jaromír Weinberger's Frühlingsstürme, Franz Lehár’s Paganini, Abraham's Ball im Savoy, Emmerich Kálmán’s Gräfin Maritza and of course Der singende Traum.
Mary's last major role was in the South African production of Tauber's Land of Smiles in 1939, but during this tour she was replaced by her understudy Jose Malone.
Despite Richard's never-wavering constancy and repeated attempts to persuade her to stop drinking, Mary virtually disappeared from public performance, barring the occasional concert fixed up by friends.
After Richard died, her financial circumstances became desperate for a while, but she found a new partner by the name of Charles Holt, and when that relationship ended, lived with a Willy Bolt in Exmouth.
In 1959, she met Vassia Myronovsky and moved into his house in the Hammersmith district of London, where she stayed until her death of cancer of the lung in July 1972.