Menachem Mendel Schneersohn (September 9, 1789 – March 17, 1866) also known as the Tzemach Tzedek (Hebrew: "Righteous Sprout" or" Righteous Scion") was an Orthodox rabbi, leading 19th-century posek, and the third Rebbe (spiritual leader) of the Chabad Lubavitch Hasidic movement.