Thomas S. Monson, the 16th president of the Mormon church, has died after overseeing the religion for nine years. He was 90.

Monson died Tuesday night at his home in Salt Lake City, according to church spokesman Eric Hawkins.

Monson spent more than five decades serving in top church leadership councils — making him a well-known face and personality to multiple generations of Mormons.

A church bishop at the age of 22, the Salt Lake City native became the youngest church apostle ever in 1963 at the age of 36. He served as a counsellor for three church presidents before assuming the role of the top leader of The Church of Jesus Christ of Latter-day Saints in February 2008.

The next president was not immediately named, but the job is expected to go to next longest-tenured member of the church's governing Quorum of the Twelve Apostles, Russell M. Nelson, per church protocol.

Monson's presidency was marked by his noticeably low profile during a time of intense publicity for the church, including the 2008 and 2012 campaigns of Mormon Mitt Romney for President. Monson's most public acts were appearances at church conferences and devotionals as well as dedications of church temples.

Monson will also be remembered for his emphasis on humanitarian work; leading the faith's involvement in the passage of gay marriage ban in California in 2008; continuing the religion's push to be more transparent about its past; and lowering the minimum age for missionaries.

Mormons considered Monson a warm, caring, endearing and approachable leader, said Patrick Mason, associate professor of religion at Claremont Graduate University in California. He was known for dropping everything to make hospital visits to people in need. His speeches at the faith's twice-yearly conferences often focused on parables of human struggles resolved through faith.

He put an emphasis on the humanitarian ethic of Mormons, evidenced by his expansion of the church's disaster relief programmes around the world, said Armand Mauss, a retired professor of sociology and religious studies at Washington State University.

"President Monson always seemed more interested in what we do with our religion rather than in what we believe," Mauss said.

A World War II veteran, Monson served in the Navy and spent a year overseas before returning to get a business degree at the University of Utah and a master's degree in business administration from the church-owned Brigham Young University.

Before being tabbed to join the faith's church's governing Quorum of the Twelve Apostles, Monson worked for the church's secular businesses, primarily in advertising, printing and publishing including the Deseret Morning News.

Monson married Frances Beverly Johnson in 1948. The couple had three children, eight grandchildren and 11 great-grandchildren. Frances died in 2013 at the age of 85.

Throughout his life, Monson was an avid fisherman who also raised homing pigeons, specifically, roller pigeons who twirled as they flew. He was known for his love of show tunes, Boy Scouts and the Utah Jazz.

Monson's legacy will be tied to the religion's efforts to hold tight to its opposition of same-sex marriage while encouraging members to be more open and compassionate toward gays and lesbians as acceptance for LGBT people increased across the county.

One of the most memorable moments of Monson's tenure came in October 2012, when he announced at church conference that the minimum age to depart on missions was being lowered to 19 from 21 for women; and to 18 from 19 for men. The change triggered a historic influx of missionaries, and proved a milestone change for women by allowing many more to serve.

The man expected to take Monson's seat, the 93-year-old Nelson, has been a church apostle since April 1970. Out of respect for Monson, his appointment will not be officially named until after his funeral services.

The Mormon church was founded in 1830 in upstate New York by Joseph Smith, who claimed he was visited by God and Jesus while praying in a grove of trees and was called to found the church. Members are known as Mormons because of the religion's keystone scripture, the Book of Mormon.