Hirsch Bär Fassel (1802-1883) (also known as Hirsch Baer Fassel or Hirsch B. Fassel) was an influential rabbi and philosopher. He was born in Boskowitz. His book Mozene Zedek, a manual for rabbis on Talmudic decisions on practical matters, urged other rabbis to be lenient in making rulings against individuals in non-criminal matters. Fassel believed that reforms in Judaism were legitimate, so long as they were brought about by rabbis.
Hirsch was a prolific writer who often had his sermons published in the Jewish press, and who was a frequent contributor to Austrian Jewish newspapers. In addition to Mozene Zedek, he wrote and published at least a dozen other books.
His manuscript of Mozene Zedek is on display at Hebrew Union College.
His daughter Rosa Sonneschein was the founder of American Jewess.