R. Moses Isserles (Rema; 1525 or 1530–1572), one of the great halakhic authorities. His full name, Isserel-Lazarus was shortened to Isserles, but he is usually referred to as "the Rema" (acronym of Rabbi Moses Isserles). Rema was born in Cracow. His father was very wealthy and a talmudic scholar. Rema was a great-grandson of R. Jehiel Luria, the first rabbi of Brisk (Brest-Litovsk). He studied first under his father and his uncle, R. Moses Heigerlich. His father sent him later to Lublin to the yeshivah of R. Shalom Shachna where he studied until 1549, marrying R. Shachna's daughter. She died in 1552 when only 20 years old, and in her memory her husband in 1553 built a synagogue, first called the Isserles synagogue and later the synagogue of the Rema, which still exists. Rema's second wife was the sister of R. Joseph ben Mordecai Gershon Ha-Kohen of Cracow, author of the responsa She'erit Yosef. Besides Talmud and the codes, Rema also studied philosophy, astronomy, and history. While still young he was renowned as an outstanding scholar and in 1550 was a member of the Cracow bet din. That year his signature appeared on a ruling along with those of R. Moses Landau and R. Joseph Katz in connection with the ban against the sale of Maimonides' works issued by the rival of R. Meir Katzenellenbogen. Rema founded a yeshivah, supporting its students from his private means. He gained a worldwide reputation as an outstanding posek and all the great scholars of the time addressed their problems to him. Among those who corresponded with him on halakhic matters were R. Meir Katzenellenbogen and his son R. Samuel Judah, R. Joseph Caro, R. Israel son of Shalom Shachna, R. Solomon Luria, and his own brother-in-law R. Joseph Katz. Among his pupils were R. David Gans, the author of Zemah David, whom Rema encouraged to study history, R. Mordecai b. Abraham Jaffe, R. Abraham ha-Levi Horowitz, father of R. Isaiah Horowitz, the author of Shenei Luhot ha-Berit, R. David b. Manasseh ha-Darshan of Cracow, R. Menahem David of Tiktin, his cousin R. Joshua Falk b. Alexander ha-Kohen, R. Aaron b. Abraham Solnik Ashkenazi, and R. Zevi Hirsch Elzisher (of Alsace?). Rema had three brothers, Isaac, Eliezer (son-in-law of R. Solomon Luria), and Joseph, and one sister, Miriam Bella the wife of R. Phinehas Horowitz. He had a son Judah Leib, and two daughters. One, Dresel, became the wife of R. Simhah Bunim Meisels, and the other, whose name is unknown, married R. Eliezer b. Simeon Ginsburg. His great granddaughter, the daughter of his grandson R. Simeon Wolf of Vilna, married R. Shabbetai b. Meir ha-Kohen.
Rema was of a humble and friendly disposition. This humility is particularly noticeable in his controversy with his older relative R. Solomon Luria. The dispute arose originally in connection with the question of the defective lung of an animal, but developed into discussions on philosophical topics, Kabbalah, and grammar. Through it was revealed Rema's self-confidence, for he held to his opinion where he was convinced he was in the right, admitted to any error, and replied with courtesy and humility. Isserles was also a scribe and wrote a Sefer Torah in accordance with the rules contained in an old manuscript which R. Joseph Caro bought for him in Erez Israel and sent to Cracow. Rema died in Cracow and was buried next to his synagogue. Until World War II thousands of Jews from every part of Poland made a pilgrimage to his grave every year on Lag ba-Omer, the anniversary of his death.