Isabelle Yakovlevna Kremer (21 October 1887 – 7 July 1956) was a soprano of Russian Jewish descent who at various times of her life held citizenship in Russia, the United States, and Argentina. She first drew notice as a teenager for her revolutionary poetry which was published in an Odessa newspaper. She began her professional singing career as an opera singer in Europe during the second decade of the 20th century. By the time of her relocation to the United States in 1924, she had abandoned her opera career in favor of performing as a concert soloist and recitalist.
As a recitalist Kremer not only sang works from the classical repertoire, but also performed folk music from a variety of countries and in many languages. She was possibly the first woman to perform Yiddish song on the concert stage. In 1927 she began performing as a vaudeville artist while continuing to perform extensively as a recitalist. In 1938, she moved to Argentina where she lived the last 18 years of her life. In 2000 her life was the subject of a television documentary entitled Isa Kremer: The People's Diva which was made for The Jewish Channel.
Kremer was born to Jewish parents in the city of Belz which was then part of the territory known as Bessarabia under Russian Imperial rule. Her father, Jacob Kremer, was a provision master in the army of Czar Nicholas II. Her mother, Anna Kremer (née Rosenbluth), was a lover of music and passed on that love to her daughter. The family was part of the bourgeois class and Isa was brought up under the care of a governess and attended a private school operated by the Russian Orthodox Church. The family moved to Odessa when Isa was 12.
As a teenager, Kremer began working as a poet; writing revolutionary poetry for a newspaper in Odessa. The newspaper's editor, Israel Heifetz, took an interest in Kremer and provided her with the funds to pursue studies in opera with Pollione Ronzi in Milan from 1902-1911. She was forced to stop studying and begin concertizing when her father's business failed; her mother came to her in Italy and she supported them both. She made her professional opera debut in 1911 at the Teatro Ponchielli in Cremona as Mimì in Giacomo Puccini's La bohème to the Rodolfo of Tito Schipa. She was then active as principal artist at the Mariinsky Theatre (then known as the Petrograd Opera) in Saint Petersburg where she starred in several operettas and was heard in various works from the concert repertoire. Some of the roles she sang there were Dolly in Franz Lehár's Endlich allein, Elvira in Lehar's Die ideale Gattin, Helen in Oskar Nedbal's Polská krev, and Laura in Karl Millöcker's Der Bettelstudent. She was later active at the Bolshoi Theatre in Moscow in 1915.