Mendel Zaks

Menachem Mendel Yosef Zaks (; 1898–1974), commonly known as Rabbi Mendel Zaks, was a prominent Lithuanian–Jewish Orthodox rabbi and professor in Byelorussia, Poland, and the United States, best known for being the professor of Talmudic studies (rosh yeshiva) at the Raduń Yeshiva, and being the son-in-law to Yisrael Meir Kagan, the Chofetz Chaim.

Early life Zaks was born in Šiluva, Rossiyensky Uyezd, Kovno Governorate, in the Russian Empire (today in Lithuania). Before joining the Raduń Yeshiva, Nowogródek Voivodeship, in Poland, he studied in the Yeshiva Knesses Beis Yitzchok while it was still in Słabódka, before it moved to Kaminetz. He was forced to leave Raduń during World War I and then studied under Reuven Dov Dessler. He also studied under Meir Simcha of Dvinsk, whose Meshech Chochmah he had helped to print.

After the war, Zaks returned to teaching in the Raduń Yeshiva, where he studied with his future father-in-law; in 1922, he married Feiga Chaya, Kagan's youngest daughter (who was 64 at the time of her birth).

Teaching career Upon the death of Naftoli Trop in 1928, Zaks was appointed rosh yeshiva to the Raduń Yeshiva, Nowogródek Voivodeship, in Poland. The outbreak of World War II forced the yeshiva to transfer to Vilna, Lithuania, and eventually Zaks re-established the yeshiva in 1943 at New York City, where he had moved with his family in 1941. Legend has it that Zaks edited the final version of the Mishnah Berurah in his office, located in the MTA building. His sons, Gershon Zaks and Hillel Zaks (rabbi in Kiryat Sefer and rosh yeshiva in Yeshivas Knesses Hagedolah, respectively), died in 1989 and 2015. His daughter, Rivka Wiesenfeld, died in 2008.