10. Prince Albert the Second, Monaco
Fortune: $1 billion
The prince's fortune includes a quarter of the land in the kingdom, a resort in Monte Carlo, an expensive stamp collection, and his mother's home, Grace Kelly, in Philadelphia, USA, which he bought in 2016 for $754,000.
9. Emir Sheikh Tamim Bin Hamad Al Thani, Qatar
Fortune: $1.2 billion
Emir Sheikh Tamim Bin Hamad Al Thani ascended to the throne in Qatar after his father Hamad Bill Kalifa Al Thani in 2013.
The fortune of former Emir Hamad Bin Qalifa Al Banyan is estimated at $2.4 billion. It comes mostly from Qatar's investment body, which manages Qatar's oil and gas reserves.
8. Grand Duke Henry of Luxembourg.
Fortune: $4 billion.
The royal family of Luxembourg does not receive a salary, but in 1948 it receives about $324,851. The royal family has received about $324,851 since 1948. You can't say they need that money, since their fortune is estimated at several billion.
7. Emir Sheikh Wariad bin Rashid Al Maktoum, Dubai, UAE
Fortune: $4.5 billion.
Wariad is the vice president and prime minister of the UAE and the Emir of Sheikh Dubai, has made a number of charitable donations for his state, such as $10 billion to build a foundation that helps future generations.
6. Prince Hans Adam II, Liechtenstein
Fortune: $5 billion
The Liechtenstein Royal Family's fortune comes largely from LGT Group Bank, which it owns, as well as from investments through their foundation, which controls foreign real estate, forests and wineries.
5. King Mohammed V, Morocco
King Mohammed Shwesta's wealth comes mainly from the fact that his family owns the Moroccan State Investment Company, which invests in other African countries and is involved in banking, telecommunications and renewable energy production.
4. Emir Khalifa bin Zayed Al Nahyan, Abu Dhabi, UAE
Wealth: $15 billion
Khalifa bin Zayed Al Nahyan, president of the UAE and emir of Abu Dhabi, succeeded in being named chairman of the Abu Dhabi Investment Authority, which manages the UAE's oil reserves.
3. King Salman bin Abdulaziz Al Saud, Saudi Arabia
Fortune: $17 billion
King Salman's family owns a media group that includes the Arabic-language daily newspapers Asharq Al-Awsat and Al Eqtisadiah.
2. Sultan Hassanal Bolkiah, Brunei
Fortune: $20 billion.
The Sultan of Brunei earns well from the oil and gas industry. He lives in the largest palace in the world worth over $350 million and is believed to own over 600 Rolls-Royce cars.
1. King Maha Vajiralonkorn, Thailand
Fortune: $30 billion
King Maha Vajiralonkorn and his family have made a fortune through investments from a government fund that manages the king's assets.
He also owns a 545-carat diamond, which is the largest in the world.