Amasa Mason Lyman (March 30, 1813 – February 4, 1877) was an early leader in the Latter Day Saint movement and was an apostle.

After becoming a Latter Day Saint, Lyman traveled 370 miles to Palmyra, New York, where he hoped to meet Joseph Smith and Martin Harris.

"As he warmly grasped my hand for the last time," Lyman later recalled, "[Smith said] brother Amasa, go and practice on the principles I have taught you, and God bless you.

In 1851, Lyman married his eighth and final wife, Lydia Partridge, a sister of his wives Caroline and Eliza.

Lyman served several missions for the church, preaching in Vermont, New Hampshire, New York, Wisconsin, Illinois, and Tennessee.

Lyman participated in the Battle of Crooked River, a skirmish between Latter Day Saints and a Missouri militia unit from Ray County, which occurred on October 25, 1838.

Due to the turbulence of the years 1843 and 1844 for the Latter Day Saints, especially after Smith's death, Lyman was never sustained at a conference of the church to this position.

In July 1844 while traveling, Lyman learned that Smith and his brother Hyrum had been killed by a mob at Carthage, Illinois.

When apostles Brigham Young, Heber C. Kimball, Wilford Woodruff, Pratt, and Lyman Wight arrived in Nauvoo on August 6, Lyman sided with the group of Latter Day Saints who supported the leadership of Young and the Quorum of the Twelve Apostles, as opposed to that of Sidney Rigdon, Smith's First Counselor in the First Presidency.

In 1847, Lyman and his seven wives and children traveled with the Mormon pioneers who followed Young to the Salt Lake Valley in present-day Utah.

[7] In March 1851, 437 Latter-day Saints under the leadership of Lyman and Rich left Great Salt Lake City.

On March 16, 1862, Lyman preached a sermon in Dundee, Scotland, which all but denied the reality of and the necessity for the atonement of Jesus Christ, which is a central tenet of the LDS Church.

His speech appeared to have been overlooked for years, but on January 21, 1867, Lyman was brought before his fellow quorum members to answer for his heretical words.

Following his removal, Lyman obeyed the counsel of the quorum members, even though he felt the advice was unappealing, and nineteen months later he was regularly attending Church services.