In the Latter Day Saint movement, the Presiding Patriarch (also called Presiding Evangelist, Patriarch over the Church, Patriarch of the Church, or Patriarch to the Church) is a church-wide leadership office within the priesthood. Among the duties of the Presiding Patriarch are to preside in council meetings, ordain other patriarchs, and administer patriarchal blessings.
Originally, the office of Presiding Patriarch was one of the highest and most important offices of the church's priesthood. The role was equated by Joseph Smith, Jr. with Biblical patriarchs from Adam to Abraham, Isaac, and Jacob, and it was expected that the office would descend through lineal succession from father to son. This precedent was set when Hyrum Smith, Joseph Smith's brother, became the second Presiding Patriarch because he was the eldest surviving son of the first Presiding Patriarch, Joseph Smith, Sr. When the office was given to Hyrum, he was given "keys of the patriarchal priesthood over the kingdom of God on earth, even the Church of the Latter Day Saints". Thus, some have argued that Presiding Patriarch is an office of the Patriarchal Priesthood. However, the existence and meaning of the Patriarchal Priesthood is controversial and uncertain.
Read more about Presiding Patriarch: The Community of Christ, Duties Within The Church of Jesus Christ of Latter-day Saints