יהודה בן קלונימוס ממגנצא

Rav Yehuda ben Kalonymus of Mainz (niftar 4956/1196), known in English sources as Judah ben Kalonymus, was a rav, posek, paytan and mekubal among the great chachmei Ashkenaz in the era of the Rishonim. English writing distinguishes two men of the Kalonymus family who carried the name — Yehuda ben Kalonymus ben Moshe of Mainz and Yehuda ben Kalonymus ben Meir of Speyer — and this is the first of them. He learned under Rav Shmarya ben Mordechai of Speyer, and the hidden Torah he received from his relative Rav Yehuda HeChasid; the sage of Speyer who shared his name was a relative as well.

He was the rosh (head) of the kehillah of Magenza — Mainz — (Germany) through the years of the Third Crusade, 4949–4952, and roused his people to teshuvah and to prepare themselves for the calamity that was coming upon them. His rulings and hora’ot are brought in the sefarim of the Rishonim, and selichot and piyutim of his are known, most of them still in manuscript. Among his foremost talmidim were his son Rav Elazar of Worms, the Rokeach; Rav Eliezer ben Yoel HaLevi, the Ra’avyah; and Rav Baruch ben Shmuel of Mainz.