Issachar ben Mordecai ibn Susan (fl. 1539–1572) (Hebrew: יששכר בן מרדכי אבן שושן) was a Jewish mathematician, living in Ottoman Palestine. At a young age, he moved from Morocco—perhaps from Fes—to Jerusalem, where he became a pupil of Levi ibn Ḥabib. From there he went to Safed, where, under great hardship, he continued his studies. But his increasing poverty induced him, in 1539, to leave Safed and seek a living elsewhere.