Mordechai Ben Yitsḥak haLevy was a 13th century rabbi and liturgical poet who emigrated from Iraq to Mainz in Germany. There, hiding in the Jewish quarter with the rest of the Jewish community of Mainz, he witnessed the terrible massacres of the Crusaders. Authorship of the popular piyyut for Ḥanukkah, Maoz Tsur, is often attributed to him on the basis of the acrostic, מרדכי found in it.