Assistant President of the Church was a position in the leadership hierarchy in the early days of the Latter Day Saint church founded by Joseph Smith. The Assistant President was the second-highest authority in the church and was a member of the church's governing First Presidency. As President of the Church, Smith appointed two men to serve in the position of Assistant President. After Smith's death, most Latter Day Saint denominations discontinued the position of Assistant President of the Church.

In the Latter Day Saint movement, the President of the Church is generally considered to be the highest office of the church. It was the office held by Joseph Smith, founder of the movement, and the office assumed by many of Smith's claimed successors, such as Brigham Young, Joseph Smith III, Sidney Rigdon, and James Strang. Several other titles have been associated with this office, including First Elder of the church, Presiding High Priest, President of the High Priesthood, Trustee-in-Trust for the church, Prophet, Seer, Revelator, and Translator. Joseph Smith was known by all of these titles in his lifetime.