David Einhorn (November 10, 1809 – November 2, 1879) was a German rabbi and leader of Reform Judaism in the United States. Einhorn was chosen in 1855 as the first rabbi of the Har Sinai Congregation in Baltimore, the oldest congregation in the United States that has been affiliated with the Reform movement since its inception. While there, he created an early American prayer book for the congregation that became one of the progenitors of the 1894 Union Prayer Book. In 1861, Einhorn was forced to flee to Philadelphia, where he became rabbi of Reform Congregation Keneseth Israel. He moved to New York City in 1866, where he became rabbi of Congregation Adath Israel.