Joseph Simon (1712–1804) was the leader of the Jewish community in Lancaster, Pennsylvania during the eighteenth century, having arrived there around 1740. By 1747, the community had enough men to support a minyan, and religious services were held at Simon's house.
Simon was a successful trader and owned enormous tracts of land in the West; among others, he was a business partner of William Henry—a gunsmith, merchant, and, later, important patriot during the American Revolution. In 1767, Thomas Barton, rector of St. James' Church in Lancaster, described Simon to Sir William Johnson as "a worthy, honest Jew and principal merchant of this place...He is esteemed a main fair in his dealings and honest from Principle."
Simon had two sons and four daughters. His granddaughter, Rebecca Gratz (1781–1869), was reputed to be one of the most beautiful women in America, and Walter Scott may have modeled Rebecca in Ivanhoe on her.
By the time Simon died at age 92 in 1804, the Jewish community in Lancaster was much depleted, having moved, in large part, to Philadelphia.