Orson Pratt, American mathematician and religious leader (born 1811)

Orson Pratt Sr. was an American religious leader and mathematician who was an original member of the Quorum of the Twelve Apostles of the Church of Christ. After the succession crisis Pratt continued in the Quorum of the Twelve of the Church of Jesus Christ of Latter-day Saints and was a leading Mormon theologian and writer until his death.