Thomas Baldwin Marsh (November 1, 1800 – January 1866) was an early leader in the Latter-day Saint movement and an original member of the Quorum of the Twelve Apostles, who served as the quorum's first president in the Church of the Latter Day Saints from 1835 to 1838. He withdrew from the church in 1838, was excommunicated from it in 1839, and remained disaffected for almost 19 years. Marsh was rebaptized into the Church of Jesus Christ of Latter-day Saints (LDS Church) in July 1857, but never again served in church leadership positions.