Leonard J. Arrington, American author and academic, founded the Mormon History Association (d. 1999)
Leonard James Arrington (July 2, 1917 – February 11, 1999) was an American author, academic and the founder of the Mormon History Association. He is known as the "Dean of Mormon History" and "the Father of Mormon History" because of his many influential contributions to the field. Since 1842, he was the first non-general authority Church Historian for The Church of Jesus Christ of Latter-day Saints (LDS Church), from 1972 to 1982, and was director of the Joseph Fielding Smith Institute for Church History from 1982 until 1986.

Arrington grew up in a large family in Idaho, where he and his family were members of the LDS Church. After high school, he studied agricultural economics at the University of Idaho and continued studying economics at the University of North Carolina at Chapel Hill. While teaching at the Utah State Agricultural College in Logan, Utah, Harvard University Press published his book Great Basin Kingdom: An Economic History of the Latter-day Saints, 1830–1900 in 1958. After a Fulbright professorship at the University of Genoa in Italy, Arrington raised funds to pay for research and writing on LDS (Mormon) biographies. He taught Western American History at Brigham Young University (BYU) from 1972 to 1987.

In conjunction with his teaching appointment at BYU, Arrington was also appointed as the first Church Historian for the LDS Church from 1972 to 1982. It was the first time a professional historian was given this job. Arrington and his team of researchers, forming the church Historical Department, began many projects to document LDS Church history, ranging from articles for the church's official magazine to scholarly books written for a non-LDS audience. The Historical Department was not subject to the church's Correlation Program and enjoyed some freedom of research. However, over time, various church members and apostles disliked the historical articles. The new director of the Historical Department, G. Homer Durham, required that all publications go through him and halted the hiring of new employees. In 1982, the LDS Church released Arrington as Church Historian and transferred the History Division to BYU, creating the Joseph Fielding Smith Institute for Church History. Arrington published over 20 books and articles, including several biographies, with the help of many research assistants.

Arrington donated his research and personal papers to Utah State University, and also donated microfilms of his pre-1982 diaries to the LDS Church Archives, with the condition that the diaries not be read until 25 years after his death. However, the LDS Church broke the agreement when shortly after Arrington's death they argued that they owned part of the collection, and asked Arrington's daughter to excise portions of Arrington's diary. After legal negotiation, half of a box of the collection was given to the LDS Church Archives.