Years: 1858–1936
Primary city: Dvinsk, Latvia
Rabbi Yosef Rosen, known as the Rogatchover Gaon, was a Chasidic Rav and posek. His encyclopedic mastery of Talmud and Rambam shaped his original derech in lomdus. Serving as Rav of a Chasidic kehillah, he produced vast chiddushim and tens of thousands of responsa, noted for their dense conceptual style and reliance on earlier Rishonim. His multi-volume Tzofnas Paneach on Rambam and on the Torah became a central expression of his method of tightly cross-referencing sugyos across Shas and halachic literature.