Ger is a Polish Hasidic dynasty originating from the town of Góra Kalwaria, Poland, where it was founded by Yitzchak Meir Alter (1798–1866), known as the "Chiddushei HaRim". Ger is a branch of Peshischa Hasidism, as Yitzchak Meir Alter was a leading disciple of Simcha Bunim of Peshischa (1765–1827). Before the Holocaust, followers of Ger were estimated to number in excess of 100,000, making it the largest and most influential Hasidic group in Poland. Today, the movement is based in Jerusalem, and its membership is estimated at 11,859 families, as of 2016, most of whom live in Israel, making Ger the largest Hasidic dynasty in Israel. However, there are also well-established Ger communities in the United States and in Europe. In 2019, some 300 families of followers led by Shaul Alter, split off from the dynasty led by his cousin Yaakov Aryeh Alter.

Hasidic Judaism in Poland is the history of Hasidic Judaism and Hasidic philosophy in Poland. Hasidic Judaism in Poland began with Elimelech Weisblum of Lizhensk (Leżajsk) (1717-1787) and to a lesser extent Shmelke Horowitz of Nikolsburg (Mikulov) (1726-1778). Both men were leading disciples of Dov Ber of Mezeritch (Medzhybizh), who in part was the successor to the Baal Shem Tov who founded Hasidic Judaism in Western Ukraine. Today, a sizable portion of contemporary Hasidic Judaism and Hasidic dynasties trace their genealogical and ideological origin to Polish Hasidism.