Fortune: $20 billionAge: 63Brunei has weathered global recession with oil production slowing, but the Sultan is trying to diversify the economy. He continues to spend lavishly, reportedly purchasing 48 handbags, 24 "duck" umbrellas from Lederer de Paris shop in 2010.

Fortune: $30 billionAge: 82As the world's longest-reigning monarch, King Adulyadej has battled personal health crises and political unrest in his country. The monarch's assets, held under the Crown Property Bureau, are composed mainly of public investments and real estate.

Fortune: $3.5 billionAge: 65As the head of a nearly 900-year-old family, the prince celebrated his 65th birthday last year with a display at Vienna's Liechtenstein Museum of roughly 140 artworks acquired during his reign, including works by Rembrandt and Rubens. Meanwhile, his country is trying to cut government expenditures to plug a budget gap of 15%.

Fortune: $450 millionAge: 84Queen Elizabeth is the oldest reigning monarch in British history and is custodian of such state-owned treasures as Buckingham Palace, the Crown Jewels and the royal art collection. Her personal fortune includes property in England and Scotland, fine art, gems and a stamp collection.

Fortune: $200 millionAge: 72Queen Beatrix celebrates 30 years on the throne this year. A surge in export revenue, recovery in real estate and a strong stock market has helped steady the royal family's fortunes.

Fortune: $100 millionAge: 42Africa's last absolute monarch assumed the throne at age 18 and maintains a tight grip on opposition with a constitution that bans political parties. He is often criticized for lavish spending, with several of his 13 wives reportedly going on million-dollar shopping sprees.

Fortune: $2.5 billionAge: 46When King Mohammed IV ascended the throne after his father's death in 1999, he focused on alleviating poverty and improving on his father's human rights record. His royal assets include a majority stake in OCP Group, the country's sole phosphate miner, as well as significant property holdings.

Fortune: $1 billionAge: 52As head of the 700-year-old Grimaldi family, Prince Albert has attempted to add to Monaco, which is smaller than New York's Central Park. The family fortune includes real estate, art, antique cars, stamps and a stake in Monte Carlo's casino. In 2010, the long-time bachelor announced his engagement to former South African Olympic swimmer Charlene Wittstock.