Satmar (or Satmar Hasidism or Satmarer Chasidism) (Hebrew: חסידות סאטמאר) is a chasidic movement composed mostly of Hungarian and Romanian Hasidic Jewish Holocaust survivors and their descendants. It was founded and led by the late Hungarian-born Grand Rebbe Yoel Teitelbaum (1887--1979), who was the rabbi of Satu Mare, Romania. The name Satmar was used by the Yiddish-speaking population, Yiddish being then the common language of the local Jews. Members of the movement are usually referred to as Satmar Chasidim or Satmarer Chasidim. The two largest Satmar communities are in Williamsburg, Brooklyn and Kiryas Joel, 

New York. There are also significant Satmar communities in Borough Park, Brooklyn and Monsey, New York. Smaller communities can be found in other North American cities such as Los Angeles, California, Montreal, Canada and in some European cities such as Antwerp in Belgium, London and Manchester in England, in Argentina, Australia and numerous cities and towns in Israel. Though he did not live in Jerusalem after 1946, the late Satmar Rebbe, Rebbe Yoel Teitelbaum, also held the title of the Chief Rabbi of Jerusalem's Edah HaChareidis.

Satmar is claimed to be one of the largest and most influential Hasidic movements in existence today, but formal demographic comparisons with other Chasidim are not available. It is believed to number close to 130,000 adherents (including men, women and children), and is rapidly growing due to the extremely high birth rate of the group. This population figure does not include a number of smaller and related anti-Zionist Hungarian Chasidic groups who align themselves ideologically with Satmar.