Rabbeinu Osher Rosh

Rabbeinu Osher ben Yechiel, the Rosh, was one of the three primary Rishonim on whom Rav Yosef Karo relied for the Shulchon Aruch. Rav Osher’s family traced its lineage to Rabbeinu Gershon. Rav Osher learned under Rav Meir of Rotenberg. After ten years as the successor of Rav Meir and the leader of German Jewry, he escaped German persecution and settled in Toledo, Spain.