Rabbi Israel of Bruna ( ; 1480-1400) was a Moravian-German rabbi and Posek (decisor on Jewish Law). He is also known as Mahari Bruna, the Hebrew acronym for "Our Teacher, the Rabbi, Israel Bruna". Rabbi Bruna is best known as one of the primary Ashkenazi authorities quoted by Moses Isserles in the Shulkhan Arukh.
Rabbi Bruna was born in Germany. He studied under the leading Ashkenazi rabbis of his time: Jacob Weil and Israel Isserlin, who ordained him and spoke very highly of him. "He was a brilliant student, who devoted himself, body and soul, to the study of the Talmud." He was then elected rabbi of Bruna. After the expulsion of the Jews from that city (1454) he settled at Ratisbon, Bavaria, where he opened a yeshivah.
His later life has been described as "eventful and troublesome".
Rabbi Bruna was one of the greatest Talmudic authorities of his time: rabbis and scholars from various cities and countries sent him their queries on all matters relating to Jewish law. These responsa, Teshuvot Mahari Bruna, are his best known work. Importantly, they served as a source of Halakha for Moses Isserles' HaMapah - the gloss on the Shulkhan Arukh describing differences between Ashkenazi and Sephardi practice. See also History of Responsa: Fifteenth century