Qatar on Sunday announced three days of national mourning after the former Emir Khalifa bin Hamad Al-Thani, who was deposed in a palace coup, died aged 84.
The former ruler died on Sunday, according to an official statement from the royal palace.
He was the grandfather of the current Emir, Tamim bin Hamad Al-Thani.
"His highness father Emir Sheikh Khalifa bin Hamad Al-Thani passed away on the evening of Sunday October 23, 2016, at the age of 84 years," read the official statement.
"His highness Sheikh Tamim bin Hamad Al-Thani has ordered public mourning across the country for three days."
No further details were given about the circumstances of his death.
Khalifa ruled Qatar from 1972 until 1995, when he was deposed by his son Hamad bin Khalifa Al-Thani in a bloodless coup while on holiday in Switzerland.
He was one of the first rulers of Qatar after it gained independence from Britain in 1971.
During his time as leader, he oversaw the beginnings of the transformation of modern-day Qatar into an energy-rich country.
He was also seen as a founding father of the Gulf Cooperation Council, the political and economic union incorporating six states in the region, including Qatar.
After being removed from power, the former emir lived in France.
He returned to Qatar in 2004.