Isadore Twersky (born Yitzchak Asher Twersky, October 9, 1930 – October 12, 1997) was an Orthodox rabbi and Hasidic Rebbe, and university professor who held the position of the "Nathan Littauer Professor of Hebrew Literature and Philosophy" at Harvard University, a chair previously held by Harry Austryn Wolfson. Twersky was an internationally recognized authority on Rabbinic literature and Jewish philosophy. He was especially known as an international expert in the writings and influence of the 12th-century Jewish legalist and philosopher Maimonides, and Abraham ben David, the Rabad of Posquieres.