Isaac Leib Peretz (Polish: Icchok Lejbusz Perec, Hebrew: יצחק־לייבוש פרץ) (May 18, 1852 – 3 April 1915), also sometimes written Yitskhok Leybush Peretz, best known as I. L. Peretz, was a Yiddish language author and playwright from Poland. Payson R. Stevens, Charles M. Levine, and Sol Steinmetz count him with Mendele Mokher Seforim and Sholem Aleichem as one of the three great classical Yiddish writers. Sol Liptzin wrote: "Yitzkhok Leibush Peretz was the great awakener of Yiddish-speaking Jewry, and Sholom Aleichem its comforter... Peretz aroused in his readers the will for self-emancipation, the will for resistance..."
Peretz rejected cultural universalism, seeing the world as composed of different nations, each with its own character. Liptzin comments that "Every people is seen by him as a chosen people..."; he saw his role as a Jewish writer to express "Jewish ideals...grounded in Jewish tradition and Jewish history."
Unlike many other Maskilim, he greatly respected the Hasidic Jews for their mode of being in the world; at the same time, he understood that there was a need to make allowances for human frailty. His short stories such as "If Not Higher", "The Treasure", and "Beside the Dying" emphasize the importance of sincere piety rather than empty religiosity.
Born in the city of Zamość, Lublin Governorate, Congress Poland, and raised in an Orthodox Jewish home he gave his allegiance at age fifteen to the Haskalah, the Jewish enlightenment. He began a deliberate plan of secular learning, reading books in Polish, Russian, German, and French. He planned to go to the theologically liberal Rabbinical school at Zhytomyr, but concern for his mother's feelings got him to stay on in Zamość. He married, through an arranged marriage, the daughter of Gabriel Judah Lichtenfeld, whom Liptzin describes as a "minor poet and philosopher".