A shtadlan was an intercessor figure starting in Medieval Europe, who represented interests of the local Jewish community, especially those of a town's ghetto, and worked as a "lobbyist" negotiating for the safety and benefit of Jews with the authorities holding power. The process of Jewish intercession is known as shtadlanut.
Typically, a Jewish community (qahal) governed its own internal affairs. The interactions with the outside society, such as tax collection and enforcement of various restrictions and compulsions imposed on the community, were arranged by an internal governing board.
The shtadlan emerged to prominence in the 17th century, with the rise of Absolutism, as an intermediator between the Jewish community and the outside government in control. The position was appointed by the government, and could even be named as a royal official. Although he officially represented the Jewish community only, the shtadlan became a tool of the government.
During the late 19th century, the use of the press and public opinion as leverage for shtadlanut activity, became the most important change in the tactics of Jewish intercession. This use was closely associated with the relief efforts for victims of pogroms in Russia and the early foundings of Political Zionism.
Traditionally, shtadlanim were seen as great protectors of the communities they affiliated with, and received approbation from the governing Jewish religious authorities.
See also 
- Francois Guesnet, Jewish political culture between East and West: Isaak Ruelf and the Transformations of intercession (shtadlanut) in the 19th century.
- See Tosafot Yom Tov on Pirkei Avot 2:3 where Rabbi Yom-Tov Lipmann Heller compares those who work on behlaf of the community to intercede with the ruling power to the likes of Mordecai in the Book of Esther and to Rabbi Judah HaNasi, codifier of the Mishna.