Years: c. 1875–1952
Primary city: Slabodka
Rabbi Yitzchak Isaac Sher was a Rosh Yeshiva of Slabodka Yeshiva in Lithuania and Bnei Brak, and the son-in-law of Rabbi Nosson Tzvi Finkel, the Alter of Slabodka. He served as Rosh Kollel of the Beis Yisrael Kollel established by his father-in-law and authored the multi-volume halachic work Beis Yisrael. He reestablished the Slabodka Yeshiva in Bnei Brak in 1947 at the advice of the Chazon Ish, together with his son-in-law Rabbi Mordechai Shulman.