Sheikh Hamad during a two-day visit to Bulgaria as part of a European tour in 2009
Sheikh Hamad bin Khalifa Al Thani, the former leader of Qatar, has died aged 74, the country's government announced on Sunday.
"The Bureau of the Emir mourns the great loss to the nation of the late, may God have mercy on him," a statement read.
Sheikh Hamad was one of the key masterminds behind modern Qatar and had taken power from his father in June 1995 in a bloodless coup.
He is credited with transforming its economy into the wealthy global powerhouse it is today, thanks to its huge natural gas reserves. Sheikh Hamad voluntarily abdicated for his son in 2013.
Funeral prayers will be held on Sunday evening before several days of public mourning across the country to mark his death.
Flags will be flown at half mast, while government officers and public institutions will be shut as a mark of respect.
When Sheikh Hamad took power 31 years ago Qatar was struggling for money with its oil reserves dwindling.
His coup - carried out while his father Sheikh Khalifa was abroad - changed the country forever.
It became a leading producer and exporter of liquefied natural gas, thanks to international partnerships and investments that had been brokered.
In 1996 Al Jazeera was launched there before becoming a big name in international broadcasting.
And Sheikh Hamad founded the Qatar Investment Authority which put money into businesses abroad, including Harrods and football team Paris Saint-Germain.
Qatar's Emir Sheikh Hamad bin Khalifa al Thani and his wife Sheikha Moza Bint Nasser al-Misnad hold a copy of the World Cup trophy after Qatar won the right to host the 2022 tournament back in 2010
It would be football where he secured one of Qatar's biggest - and controversial - triumphs.
The country was awarded the right to host the 2022 World Cup in 2010, despite allegations of corruption it was later cleared of.
It hired 30,000 foreign labourers just to build the stadiums. In 2021 it was reported some 6,500 migrant workers from India, Pakistan, Nepal, Bangladesh and Sri Lanka had died since it won the World Cup bid.
The Qatar government said not all the deaths recorded were of people working on World Cup-related projects and many had lived there a long time.
There was also criticism over Qatar's human rights record and laws against same-sex relationships.
Qatar was a British protectorate until 1971, with the Al Thani family as monarchs since 1851.
