Louis Buchalter, known as Louis Lepke or Lepke Buchalter, was a Jewish-American organized crime figure and head of the Mafia hit squad Murder, Inc., during the 1930s. Buchalter was one of the premier labor union racketeers in New York City during that era.

Jewish-American organized crime initially emerged within the American Jewish community during the late 19th and early 20th centuries. In media and popular culture, it has variously been referred to as the Jewish Mob, the Jewish Mafia, the Kosher Mob, the Kosher Mafia, the Yiddish Connection, and Kosher Nostra or Undzer Shtik. The last two of these terms are direct references to the Italian cosa nostra; the former is a play on the word for kosher, referring to Jewish dietary laws, while the latter is a calque of the Italian phrase 'cosa nostra' into Yiddish, which was at the time the predominant language of the Jewish diaspora in the United States.