Mario S. De Pillis (January 22, 1926, in Philadelphia, Pennsylvania - November 18, 2021) was an emeritus professor of American Religious history at the University of Massachusetts Amherst. De Pillis specialized in the history of such groups as the Latter-day Saints and Shakers. He was the second president of the Mormon History Association who was not a member of The Church of Jesus Christ of Latter-day Saints, any other Latter-day Saint movement church, or a former member of any such church.