Lazar Horowitz, or Eleazar HaLevi Ish Horowitz, Eleasar ben David Josua Hoeschel Horowitz, aka El'azar Hurwitz  (1803/1804, Floß, Upper Palatinate - June 11, 1868, Vöslau) was an Orthodox Rabbi who led the Orthodox Jewish community of Vienna during the Vormärz period.
Born in Bavaria, Horowitz was a student of Moses Sofer of Pressburg before moving to Vienna in 1828 to serve as the community's supervisor of Kosher meat. There, he collaborated with Reform Jewish rabbis of his day, such as Isaak Noah Mannheimer and Adolph Jellinek regarding synagogue protocol in the central synagogues of Vienna. In 1829, he drafted the bylaws of the central Stadttempel. Although he himself was an Orthodox Jew, he continued to pray occasionally in the Reform temple.
Horwitz wrote a book of halakhic responsa called "Yad Eleazar."
His responsum regarding metzitzah b'peh was strongly influenced by the Hatam Sofer's rulings, according to Meir Hershkovitz in his 1972 article on Horwitz.
In 1863, Horowitz defended Heinrich Graetz in Viennese court when Graetz was accused of heresy for an article he had published in a local journal. Graetz had written that the chapters in Isaiah referring to the Messiah were meant to be interpreted non-literally, and that they referred to a national Messiah instead of a personal one. Other Orthodox rabbis, including Azriel Hildesheimer, criticized Horowitz for defending Graetz, arguing that it was inapproproate for an Orthodox rabbi to defend the theology of a Positive-Historical historian, no matter what the historian had written.
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