Shloyme Zanvl Rappoport (1863, Chashniki –1920, Otwock), known by his pseudonym S. Ansky (or An-sky), was a Russian Jewish author, playwright, researcher of Jewish folklore, polemicist, and cultural and political activist.

S. Ansky was born in Chashniki, Belarus, then part of the Russian Empire. Initially he wrote in Russian, but from 1904, he became known mainly as a Yiddish author.

Under the influence of the Russian narodnik movement, Ansky became interested in ethnography, as well as socialism, and became a political activist. After the 1917 Russian Revolution he was elected to the All-Russian Constituent Assembly as a deputy of the Social-Revolutionary Party.

Between 1911 and the outbreak of the Great War in 1914, he headed ethnographical expeditions to various Jewish towns of Volhynia and Podolia, composing a detailed ethnographic questionnaire of more than 2000 questions.

He is best known for his play The Dybbuk or Between Two Worlds. The play was first staged in the Elyseum Theatre in Warsaw two months after the author's death in Otwock on November 8, 1920. It was subsequently translated into a dozen or more languages and performed thousands of times all over the world. It is still being produced, along with numerous adaptations, as well as operas, ballets, and symphonic suites. (For example in 2011 there were seven different productions.) It is considered the jewel of the Jewish theatre.[2] In the early years The Dybbuk was considered so significant that parodies of it were written and produced.

Although The Dybbuk is An-sky’s best-known work, he published an impressive number of works of literature, politics and ethnography. His Collected Works, which do not include all his writings, comprise fifteen volumes. An-sky wrote a number of other plays, four of which are included in this collection, long out of print. One (“Day and Night”) is, like The Dybbuk, a Hasidic Gothic story. The other three plays have revolutionary themes, and were originally written in Russian: “Father and Son.” “In a Conspiratorial Apartment,” and “The Grandfather.” All four have recently been republished in a bilingual Yiddish-English edition.

Ansky was also the author of the song Di Shvue (The Oath), which became the anthem of the Jewish Socialist Bund party. He was the author of the poem (later made into a song) In Zaltsikn Yam (In the Salty Sea), which was dedicated to the Bund as well.
Mausoleum of the Three Writers (Peretz, Dinezon, and Ansky) in Warsaw

Ansky's ethnological collections were locked away in Soviet vaults for years, but some material has come to light since the 1990s. The State Ethnographic Museum at St. Petersburg holds a good deal of it.

Some of his vast collection of cylinder recordings made on these expeditions have been transferred to CD as well.

His ethnographic report of the deliberate destruction of Jewish communities by the Russian army in the First World War, The Enemy at His Pleasure: A Journey Through the Jewish Pale of Settlement During World War I, has become a major source in the historiography of the war's impact on civilian populations.

In 1917 he was elected to the Russian Constituent Assembly as a Social-Revolutionary deputy.