Russell Marion Nelson Sr. was an American cardiac surgeon, cardiologist, and religious leader who served as the seventeenth president of the Church of Jesus Christ of Latter-day Saints.

Born on September 9, 1924, in Salt Lake City, Nelson pursued an extensive medical education, studying at the University of Utah, the University of Utah School of Medicine, and the University of Minnesota. He went on to work as a cardiac surgeon, cardiologist, and military physician before his career took a decisive turn toward full-time religious service. His dual formation — rigorous scientific training alongside deep ecclesiastical commitment — defined the trajectory of his adult life.

Nelson was called to the Quorum of the Twelve Apostles, one of the governing bodies of the Church of Jesus Christ of Latter-day Saints, and served as a member of that quorum for nearly thirty-four years. He became the quorum's president in 2015, a position he held until 2018, when he was sustained as the church's seventeenth president following the death of his predecessor. In that office, the church recognized him as prophet, seer, and revelator — the highest designations conferred within its ecclesiastical structure. He held that position until his death on September 27, 2025, in Salt Lake City, at the age of one hundred and one. He had been born in the same city, and it was there that his life also ended, a symmetry that marked the full span of a long and publicly prominent career.

Among the details that distinguished Nelson's work and presence was his demonstrated facility with languages. In addition to English, he used Russian, French, and Spanish — a range that reflected the international scope of a church with a global membership and the demands placed on its senior leadership to communicate across linguistic and cultural boundaries. His biography, as catalogued in the Library of Congress Name Authority File under the authorized label Nelson, Russell M. (Russell Marion), 1924–2025, documents a life that moved between the operating theater and the pulpit, between the precision of surgical medicine and the responsibilities of institutional religious leadership at its highest level.