Menashe Klein (1924–2011) (Hebrew: ?' ???? ?????), also known as the Ungvarer Rav (Yiddish: ?????????? ??), was a Hasidic Rebbe and posek (arbiter of Jewish law).
He authored 18 volumes of responsa, spanning over 50 years, entitled Mishneh Halachos.
Additionally, he authored some 25 other seforim, including a commentary on Simeon Kayyara's BeHag.
Toward the end of his life, he relocated from Brooklyn, New York to Jerusalem.