R. Isaac Meir Alter (also Rottenburg, Rothenburg or Rothenberg as an alternate for "Alter") (1798 - March 10, 1866), was also known as the Hidushei Harim for his Torah works. He is sometimes referred to fondly as Reb Itche Myer by his followers. He was an Orthodox Jewish rabbi and founder of the Ger (Hasidic dynasty) within Hasidic Judaism in the town of Góra Kalwaria (Ger in Yiddish), Poland. He came from a very distinguished family of rabbis, among the most prominent in Germany and Poland. He was a descendant of Rashi, and R. Meir ben Baruch of Rothenburg (1215 - 1293) the Tosafist. He is considered to be the first rebbe (Hasidic spiritual leader) of the Ger Hasidic dynasty.

R. Isaac Meir was born in Magnuszew, Poland, in late 1798. He married Feigele Lipszyc, daughter of Moshe 'Halfon' Lipszyc, in 1811. They had fourteen children (according to most published sources), most of whom died in infancy. R. Isaac Meir became known as a Talmudic genius. At first he was close to the rebbes of Kozhnitz. After some years he was drawn to the Rebbe Reb Simcha Bunim of Prshischa whose close adherent he became. After the demise of the Rebbe Reb Binem, R. Isaac Meir, in common with many of the former's chasidim, became a disciple of Rabbi Menachem Mendel of Kotzk, known as the Kotzker rebbe, who was famous for his acerbic wit and Talmudic brilliance. The two eventually became brothers-in-law, when the Kotzker Rebbe married Chaya Lipszyc, sister of Rabbi Yitschok Myer's wife Feigele. R. Isaac Meir Alter was succeeded by his colleague and disciple Rabbi Chanoch Henoch of Alexander. ne son, Avrohom Mordechai, and three daughters, Cyna Pesia, Leah Hudes and Esther, survived to adulthood and married. By the time of Yitschok Myer's death on 23 Ador 5626 (1866), only one child (Esther) remained alive.

פיעטרקוב, נסדר בדפוס חנוך העניך פאלמאן (דפוס י. וואגמייסטער), שנת ז'כ'ר' צ'ד'י'ק' ל'ב'ר'כ'ה' [תרפ"ח]. [2], 118 עמ'.