Sabbatai Zevi (Hebrew: שַׁבְּתַי צְבִי, romanized: Šabbəṯay Ṣəḇī, August 1, 1626 – c. September 17, 1676) was an Ottoman former Jewish mystic and rabbi from Smyrna who converted to Islam. His family were Romaniote Jews from Patras.
Active throughout the Ottoman Empire, Zevi claimed to be the long-awaited Jewish Messiah and founded the Sabbatean movement. Central to his teachings was the belief that during the Messianic Age, acts traditionally considered sinful would transform into righteous ones. This antinomian doctrine led Zevi and his followers to deliberately violate Jewish commandments, a controversial practice that later inspired movements like the Frankists.