Rabbi Mordechai ben Hillel (c. 1250-1298) was one of the great halachic authorities of Ashkenaz in the generation after the Tosafists. He belonged to one of the most prominent scholarly families of Germany, descended from the Raavan and the Raavyah, and was related to the Rosh. His principal teacher was the Maharam of Rothenburg, and he also studied under Rabbeinu Peretz of Corbeil. He is sometimes called "HaKohen", but Professor Simcha Emanuel has shown that he was not a kohen.

His work, Sefer HaMordechai, known simply as "the Mordechai", is a vast collection of rulings and responsa of the sages of Ashkenaz and France, arranged in the order of the Talmud and printed after the Rif in editions of the Talmud. It preserves many teachings that would otherwise have been lost, was a major source for the Rema, and is one of the sources of the Shulchan Aruch.

From 1291 he was rabbi and rosh yeshiva of Nuremberg. He died a martyr on 22 Av 5058 (1298), with his wife Zelda and their five children, in the Rindfleisch massacres. A seventeenth-century Jerusalem tradition holds that his remains were brought to the Land of Israel and buried on the Mount of Olives, in the cave of Rabbi Ovadia of Bartenura.