A Rebbe or Admor is the spiritual leader in the Hasidic movement, and the personalities of its dynasties. The titles of Rebbe and Admor, which used to be a general honor title even before the beginning of the movement, became, over time, almost exclusively identified with its Tzadikim.

Hasidism, sometimes spelled Chassidism, and also known as Hasidic Judaism, is a religious movement within Judaism that arose as a spiritual revival movement in Poland and contemporary Western Ukraine, during the 18th century, and spread rapidly throughout Eastern Europe. Today, most of those affiliated with the movement, known as hassidim, reside in Israel and in the United States.