Joshua ben Alexander HaCohen Falk (1555 – 29 March 1614) was a Polish Halakhist and Talmudist, best known as the author of the Beit Yisrael commentary on the Arba'ah Turim as well as Sefer Me'irat Enayim (סמ"ע) on Shulkhan Arukh. His name also occurs as the Hebrew acronym רפ"כ ("RaFaC") ("Rabbi Falk Cohen" and מהרו"כ ("Ma-HaRWaC") ("Morenu ha-Rab Walk Cohen").
He was a pupil of his relative Moses Isserles and of Solomon Luria, and became the head of the yeshiva of Lemberg. Many celebrated rabbis were his pupils, among them being Joshua Höschel ben Joseph of Kraków, the author of "Maginne Shelomoh". Falk was a great authority on rabbinical matters. At the meeting of the Council of Four Lands in 1607, during the Kremenetz fair, many of his proposals were approved. In 1611 Falk and Enoch Hendel ben Shemariah issued a bill of divorce at Vienna which occasioned lengthy discussions among the celebrated rabbis of the time, including Meir Lublin and Mordecai Yoffe (see "She'elot u-Teshubot MaHaRaM", Nos. 123 et seq.). He was Rosh Yeshiva in Lemberg and served on the Council of Four Lands.
Falk was opposed to the reliance on law codes to the exclusion of study of the original sources. Towards this end he composed a series of commentaries on the most influential codes, Rabbi Jacob ben Asher's Tur and Rabbi Joseph Karo's Shulkhan Arukh. He spent his early life composing extensive analytical commentaries on the Talmud, which were later lost in a fire.