Gordon Hinckley, president of the Church of Jesus Christ of Latter-Day Saints, has died, aged 97.
Gordon Hinckley (left) had been president for 13 years
He was president of the Church - better known as the Mormons - for 13 years.
The post is held for life, and Hinckley lived to become the oldest ever president, seeing church membership expand to 13 million people.
His death comes amid increased public scrutiny of the Church, as one of its members, former Massachusetts Governor Mitt Romney, runs for US president.
Based in Utah, half of the LDS membership is now drawn from outside the United States.
By tradition, a new Church president must be ordained within days on a unanimous vote of the Council of the Twelve Apostles, which is likely to wait until after his funeral.
The current most long-serving apostle is Thomas Monson, aged 80, The Associated Press reports.
Hinckley died of complications arising from old age, Church spokesman Mike Otterson said.
"His life was a true testament of service, and he had an abiding love for others," said Senator Orrin Hatch of Utah, a fellow Mormon.
"His wit, wisdom, and exemplary leadership will be missed by not only members of our faith, but by people of all faiths throughout the world."
Hinckley was ordained as the 15th president of the LDS in March 1995.
He travelled the world extensively, dedicating LDS temples.
Diagnosed with diabetes, he was hospitalised in January 2006 for the removal of a cancerous growth in his large intestine.
In April 2006, he told a Church conference he was "totally in the hands of the Lord".