Isidor Kalisch (15 November 1816 – 11 May 1886), born in Krotoschin, Prussia, was a prominent Reform movement rabbi and writer in the United States. He was educated at Berlin, Breslau (Wrocław) and Prague. While pursuing his studies in theology and philosophy, he contributed to German periodicals. In 1842 he wrote a patriotic poem, entitled "Schlacht-Gesang der Deutschen" (Battle song of the Germans) which was set to music and became one of the popular songs of the day. In 1843, he preached the first German sermon ever delivered in his native town. During the Revolutions of 1848, he first came to London, and in 1849 to the United States. In 1850, was came the Tifereth Israel congregation in Cleveland, Ohio. In 1855, the first conference of rabbis was held in Cleveland, and a ritual and common prayer-book was agreed upon, entitled Minhag America, which he edited together with Rabbi Isaac Mayer Wise and found use in many synagogues. In 1855, he was requested by Prof. Josiah W. Gibbs, of Yale University, to decipher a Phoenician inscription that had been found in Sidon, Asia. His rendering of it was read before the Syro-Egyptian Society of London, 13 November 1855. From 1856 to 1860, he took a pulpit in Milwaukee, Wisconsin where he united two factions and organized Die treue Schwestern (the true Sisters), a benevolent society of Jewish women. Afterward, he held pulpits in Indianapolis; Detroit; Leavenworth, Kansas; Newark, New Jersey; and Nashville, Tennessee where he erected a synagogue.
He returned to Newark in 1875, and devoted himself to literary work and to lecturing, taking part in polemical discussions in behalf of the ultra-reform element in Judaism. He took issue with Isaac Leeser's English translation of the Ḥumash, and on the "Jewish Belief in a Personal Messiah." From 1853 until 1878 he edited the Guide, and contributed a great number of essays and discourses to German and English religious periodicals.