Rabbi Joseph ben Mordechai Gershon HaKohen Ka"tz (1510 in Cracow – 1591), a kohen by birth, rabbi and Talmudist, began his studies in the Talmud at an early age, and became the rosh yeshivah founded for him by his father-in-law. The many pupils who attended this school soon made him famous for his scholarship; and his views on religious questions were widely sought. Solomon Luria was one of his correspondents.
Joseph was the author of "She'erit Yosef" (Cracow, 1590), containing responsa and discussions on various rabbinical subjects, as well as a commentary on the "Mordechai" tractates Nezikin, Berakot, and Mo'ed. In the preface the author states that he published this work at the request of his sons, Tanhuma and Aaron Moses, who were members of the Jewish community of Cracow. He also corrected the manuscript from which was printed the "Aggudah" of Alexandri HaKohain of Frankfurt.