Hasdai ben Abraham Crescas (Catalan: [həzˈðaj ˈβeɲ ʒuˈða ˈkɾeskəs]; Hebrew: חסדאי קרשקש; c. 1340, in Barcelona – 1410/11, in Zaragoza) was a Spanish-Jewish philosopher and a renowned halakhist (teacher of Jewish law). Along with Maimonides ("Rambam"), Gersonides ("Ralbag"), and Joseph Albo, he is known as one of the major practitioners of the rationalist approach to Jewish philosophy.
Hasdai Crescas came from a family of scholars. He was the grandson of the Talmudist Hasdai ben Judah Crescas, and a disciple of the Talmudist and philosopher Nissim ben Reuben, known as The RaN. Following in the footsteps of his teacher he became a Talmudic authority and a philosopher of great originality. He is considered important in the history of modern thought for his deep influence on Baruch Spinoza.
After leaving Barcelona, he held the administrative position of crown rabbi in Aragon. He seems to have been active as a teacher. Among his fellow students and friends, Isaac ben Sheshet (known as the RIBaSH), famous for his responsa, takes precedence. Joseph Albo is the best known of his pupils, but at least two others have won recognition, Rabbi Mattathias of Saragossa, and Rabbi Zechariah ha-Levi.