Menachem Mendel Auerbach (Ateret Zekenim)

Menachem Mendel Auerbach was a late-17th-century Ashkenazic halakhist who wrote Ateret Zekenim, a short, sharp set of notes (glosses) on the daily-practice section of the Shulchan Aruch, the standard code of Jewish law (Orach Chaim). Slim as it was, later scholars (the Acharonim) kept quoting it for generations.