William E. McLellin (1806-1883) was an early Mormon apostle.

William E. McLellin was born January 18, 1806 in Smith County, Tennessee to parents Charles McLellin and Sarah (a Cherokee Indian). In 1829, he married Cynthia Ann, but she died by the summer of 1831. On August 20, 1831, he was baptized into The Church of Jesus Christ of Latter-day Saints by Hyrum Smith. He married Emeline Miller in 1832 at Portage County, Ohio, and they had six children together. Together they moved to Independence, Missouri in 1832. Later that year in December, McLellin was excommunicated for the first time. In 1833, with membership reinstated, he left his family to serve missions in Missouri and Illinois with Parley P. Pratt. He and his family also fled from persecution in Jackson County into Clay County, Missouri. McLellin moved to Ohio where he was appointed as an instructor for the Kirtland School on November 19, 1834.

He was ordained a member of the Quorum of the Twelve Apostles on February 15, 1835. Soon after he was disfellowshipped, but had his membership reinstated in 1835. A year later he wrote a letter withdrawing his membership from the Church, but in 1837 was sustained to Quorum of the Twelve again. He was finally excommunicated in 1838 and broke with all organized religion in 1869. In 1837, he was a commissioned captain in the Missouri State Militia. Throughout his life he associated with splinter groups of The Church of Jesus Christ of Latter-day Saint and unsuccessfully tried to start one of his own. Though disillusioned with Joseph Smith and disbelieving in his role as a prophet of God, McLellin's writings show that he maintained faith and testimony in The Book of Mormon and other Latter-day Saint teachings throughout his life.

He moved back to Independence, Missouri in 1870 and died there in 1883.