Shtetl or shtetel (English: /ˈʃtɛtəl/ SHTET-əl; Yiddish: שטעטל, romanized: shtetl, pronounced [ʃtɛtl̩]; pl. שטעטעלעך shtetelekh) is a Yiddish term for small towns with predominantly Ashkenazi Jewish populations which existed in Eastern Europe before the Holocaust. The term is used in the context of former Eastern European Jewish societies as mandated islands within the surrounding non-Jewish populace, and thus bears certain connotations of discrimination. Shtetls (or shtetels, shtetlach, shtetelach or shtetlekh) were mainly found in the areas that constituted the 19th-century Pale of Settlement in the Russian Empire (constituting modern-day Belarus, Lithuania, Moldova, Ukraine, Poland, Latvia and Russia), as well as in Congress Poland, Austrian Galicia and Bukovina, the Kingdom of Romania and the Kingdom of Hungary.

In Yiddish, a larger city, like Lviv or Chernivtsi, is called a shtot (Yiddish: שטאָט), and a village is called a dorf (Yiddish: דאָרף). Shtetl is a diminutive of shtot with the meaning 'little town'. Despite the existence of Jewish self-administration (kehilla/kahal), officially there were no separate Jewish municipalities, and the shtetl was referred to as a miasteczko or miestelis (mestechko, in Russian bureaucracy), a type of settlement which originated in the former Polish–Lithuanian Commonwealth and was formally recognized in the Russian Empire as well. For clarification, the expression "Jewish miasteczko" was often used.

The shtetl as a phenomenon of Ashkenazi Jews in Eastern Europe was destroyed by the Nazis during the Holocaust. The term is sometimes used to describe largely Jewish communities in the United States, such as existed on the Lower East Side of New York City in the early 20th century, and predominantly Hasidic communities such as Kiryas Joel and New Square today.

A shtetl is defined by Yohanan Petrovsky-Shtern as "an East European market town in private possession of a Polish magnate, inhabited mostly but not exclusively by Jews" and from the 1790s onward and until 1915 shtetls were also "subject to Russian bureaucracy", as the Russian Empire had annexed the entire Lithuania and the eastern part of Poland, and was administering the area where the settlement of Jews was permitted. The concept of shtetl culture describes the traditional way of life of East European Jews. In literature by authors such as Sholem Aleichem and Isaac Bashevis Singer, shtetls are portrayed as pious communities following Orthodox Judaism, socially stable and unchanging despite outside influence or attacks.

The history of the oldest Eastern European shtetls began around the 13th century. Throughout this history, shtetls saw periods of relative tolerance and prosperity as well as times of extreme poverty and hardships, including pogroms in the 19th-century Russian Empire. According to Mark Zborowski and Elizabeth Herzog (1962):

The attitudes and thought habits characteristic of the learning tradition are as evident in the street and market place as the yeshiva. The popular picture of the Jew in Eastern Europe, held by Jew and Gentile alike, is true to the Talmudic tradition. The picture includes the tendency to examine, analyze and re-analyze, to seek meanings behind meanings and for implications and secondary consequences. It includes also a dependence on deductive logic as a basis for practical conclusions and actions. In life, as in the Torah, it is assumed that everything has deeper and secondary meanings, which must be probed. All subjects have implications and ramifications. Moreover, the person who makes a statement must have a reason, and this too must be probed. Often a comment will evoke an answer to the assumed reason behind it or to the meaning believed to lie beneath it, or to the remote consequences to which it leads. The process that produces such a response—often with lightning speed—is a modest reproduction of the pilpul process.

The May Laws introduced by Tsar Alexander III of Russia in 1882 banned Jews from rural areas and towns of fewer than ten thousand people. In the 20th century, revolutions, civil wars, industrialisation and the Holocaust destroyed traditional shtetl existence.

The decline of the shtetl started from about the 1840s. Contributing factors included poverty as a result of changes in economic climate (including industrialisation which hurt the traditional Jewish artisan and the movement of trade to the larger towns), repeated fires destroying the wooden homes, and overpopulation. Also, the antisemitism of the Russian Imperial administrators and the Polish landlords, as well as the resultant pogroms in the 1880s, made life difficult for residents of the shtetl. From the 1880s until 1915 up to 2 million Jews left Eastern Europe. At the time about three-quarters of its Jewish population lived in areas defined as shtetls. The Holocaust resulted in the total extermination of these towns. It was not uncommon for the entire Jewish population of a shtetl to be rounded up and murdered in a nearby forest or taken to the various concentration camps. Some shtetl inhabitants were able to emigrate before and after the Holocaust, which resulted in many Ashkenazi Jewish traditions being passed on. However, the shtetl as a community of Ashkenazi Jews in Eastern Europe, as well as much of the culture specific to this way of life, was all but eradicated by the Nazis.