Mordechai Breuer (1921 – February 24, 2007) (Hebrew: מרדכי ברויאר‎) was an Orthodox rabbi. He was one of the world's leading experts on Tanakh (Hebrew Bible), especially in the ancient Aleppo Codex version.

He produced two editions of the Tanakh with text and formatting based on those of the Aleppo Codex (including a reconstruction of its missing parts).

Breuer's method is the basis of the modern edition of the Tanakh known as Keter Yerushalayim (כתר ירושלים "The Jerusalem Crown"), printed in Jerusalem in 2000, referred to in English as the Jerusalem Codex. This text is now the halakhic standard that scribes use, and the official Tanakh of the Israeli government.

Breuer was a great-grandson of Rabbi Samson Raphael Hirsch and winner of the Israel Prize in 1999 for original Torah research.

He was known for developing Shitat Habechinot ("the aspect approach") which suggests that differing styles and internal tensions in the Biblical text represent different aspects of God or Torah, which cannot be merged without losing their identity. According to Breuer, God wrote the Torah from "multiple perspectives ... each one constituting truth, [for] it is only the combination of such truths that gives expression to the absolute truth."^[1]

In his two volume book Pirkei Moadot (1986), Rabbi Breuer discusses twenty eight topics, mostly holidays like the Sabbath, Pesach, Shevuot, and Hannukah. The majority of the essays address the peshat or simple understanding of the Biblical text (written law) and attempts to clarify how it corresponds with the halakha or rabbinic law. A few of the essays address issues of oral law. For example, in one of his essays on Pesach, he discusses why and how the order of the Pesach Seder has changed since the destruction of the Temple. Originally, the korban Pesach (Passover sacrifice) was eaten after saying Kidush and drinking the first glass of wine. He explains how and why the seder developed as presented in the Hagadah nowadays. In the introduction, he articulates his methodology for ascertaining the peshat of the Biblical text and demonstrates this method in several of the essays.^[2]