Orson Pratt, American mathematician and religious leader (d. 1881)

Orson Pratt Sr. (September 19, 1811 – October 3, 1881) was an American mathematician and religious leader who was an original member of the Quorum of the Twelve Apostles of the Church of Christ (Latter Day Saints). He became a member of the Quorum of the Twelve of The Church of Jesus Christ of Latter-day Saints (LDS Church) and was a leading Mormon theologian and writer until his death.