Reuben Osborne Moon (July 22, 1847 – October 26, 1919) was a Republican member of the U.S. House of Representatives for Pennsylvania. Moon was born in Jobstown, New Jersey. He graduated from the , in Philadelphia, Pennsylvania, in 1874. He became a professor in the National School of Oratory, and engaged in lecturing and studied law. He was admitted to the bar in 1884 and commenced practice in Philadelphia. He was one of the founders and president of the Columbia Club. He died in Philadelphia on October 26, 1919. He is interred at West Laurel Hill Cemetery in Bala Cynwyd, PA.