Isser Zalman Meltzer (1870 – November 17, 1953), was a famous Lithuanian Orthodox rabbi, rosh yeshiva and posek. He is also known as the "Even HaEzel"—the title of his commentary on Rambam's Mishne Torah.
Rabbi Meltzer was born in the city of Mir, in what is today Belarus. His father, Baruch Peretz, was also a rabbi. From the age of 10, he studied with Rabbi Yom-tov Lipman, the rabbi of the city, and at the Mir Yeshiva. At the age of 14, he began studying at the Volozhin yeshiva under the Netziv and Rabbi Chaim Soloveitchik, where he remained for seven years.
While at the yeshiva, he became involved in the secret [Orthodox] Ness Ziona Society, part of the Hovevei Zion movement. Together with his brother-in-law, Rabbi Moshe Mordechai Epstein, he contributed to the founding of the city of Hadera by buying land for an etrog orchard.
In 1894, Rabbi Melzer became a maggid shiur at the Slabodka yeshiva, together with his brother in law, Rabbi Epstein. In 1897, Rabbi Meltzer left Slabodka to lead another yeshiva which had been established by the Ridvaz in Slutsk.
In 1903, Rabbi Meltzer was appointed as the Rabbi of Slutsk, a position he held for 20 years. Although he had already been serving as the rosh yeshiva in that city, he had no document of semicha because he had never planned on accepting a position in the rabbinate, but to teach Torah instead. When the communal leaders resolved to appoint him as their rabbi, Rabbi Meltzer wrote to his teacher Rabbi Chaim Soloveitchik and to Rabbi Yechiel Michel Epstein, author of the Arukh HaShulkhan, asking them to send him the necessary affirmation. Rabbi Epstein immediately mailed him a letter of semicha, while Rabbi Soloveitchik made do with a brief telegram that simply bore the words, "Yoreh yoreh, yodin yodin".
Rabbi Meltzer was also a disciple of the Chofetz Chaim and Rabbi Nosson Tzvi Finkel. He was the father-in-law of Rabbi Aharon Kotler and maternal grandfather of Rabbi Shneur Kotler. Rabbi Meltzer was a friend and admirer of Rabbi Avraham Yitzhak Hacohen Kook, the chief rabbi of Palestine and a self-avowed supporter of Zionism. In his later years, Rabbi Meltzer served as the rosh yeshiva of the Etz Chaim Yeshiva in Jerusalem. He died on Tuesday, 17 November (10th Kislev) 1953, and was interred on Har HaMenuchot.
The legacy of Rabbi Meltzer was carried on by his numerous students:His son, Rabbi Zvi Yehuda Meltzer, Chief Rabbi of Rehovot, and the father-in-law of Rabbi Yehuda Amital
His son, Rabbi Dr. Professor Feivel Meltzer was a noted linguist of Biblical Hebrew in Israel and contributor to the Da’at Miqra commentary on the Tanach
His son-in-law, Rabbi Yitzchack Ben Menachem, Chief Rabbi of Petah Tikva
His son-in-law, Rabbi Aharon Kotler, founder of Bais Medrash Gevoha in Lakewood, New Jersey
His granddaughter's husband, Rabbi Yehuda Amital, rosh yeshiva of Yeshivat Har Etzion.
Rabbi Shlomo Zalman Auerbach, rosh yeshiva of Kol Torah and leading posek of his time.
Rabbi Yisroel Yaakov Fisher
Rabbi Shlomo Goren, former Ashkenazi Chief Rabbi of Israel.
Rabbi Yosef Eliyahu Henkin, founder of Ezras Torah
Rabbi Moshe Aharon Poleyeff, rosh yeshiva of Yeshiva University.
Rabbi Elazar Shach, rosh yeshiva of Ponevezh Yeshiva in Israel, and leader of Lithuanian Jews
Rabbi Avraham Yaakov Zelaznik, rosh yeshiva of Yeshiva Etz Chaim.
Rabbi Shimon Zelaznik, (the above's brother) rosh yeshiva in Yeshivat Shaalvim
Rabbi Amram Zaks, rosh yeshiva of the Slabodka yeshiva of Bnei Brak
Rabbi Isaac L. Swift