In Forbes's annual list of the net worth of "Kings, Queens & Dictators," Fidel Castro is listed as having $900 million (tip to Betsy). USAToday reports:

Cuban President Fidel Castro was furious when Forbes magazine estimated his fortune at $550 million last year. This year, the magazine upped its estimate of the communist leader's wealth to a cool $900 million. Castro, who says his net worth is nil, is likely the beneficiary of up to $900 million, based on his control of state-owned companies, the U.S. financial magazine said in its annual tally of "Kings, Queens & Dictators" fortunes Thursday.

Kings and sheikhs of the oil-rich Gulf Arab states still top the Forbes list, to be published in its May 22 edition.

Saudi King Abdullah is number one with an estimated $21 billion, followed by Sultan Hassanal Bolkiah of Brunei at $20 billion and United Arab Emirates' President Sheikh Khalifa bin Zayed al-Nahayan at $19 billion.

Among Europeans, Prince Hans-Adam II of Liechtenstein improved upon his family fortune of palaces, real estate and artwork with an investment in a U.S. producer of hybrid rice, for total estimated riches of $4 billion.

Perhaps the most industrious of the leaders listed is Sheikh Mohammed bin Rashid al-Maktoum, ruler of Dubai, with a net worth of $14 billion.

Forbes estimates the renowned racehorse breeder also helped raise Dubai's gross domestic product from about $8 billion to nearly $40 billion since 1994 by diversifying its industries outside of oil and making successful investments overseas.

"He would probably be the shrewdest of the bunch," said Luisa Kroll, associate editor at Forbes.

Forbes requires registration to read the story, which if you follow an internal link for 10 rich heads of state eventually leads to this entry on Castro:

Fidel Castro
President/Cuba
$900 million
Age: 79

Comandante since 1959. We estimate his fortune based on his economic power over a web of state-owned companies including El Palacio de Convenciones, a convention center near Havana; Cimex, retail conglomerate; and Medicuba, which sells vaccines and other pharmaceuticals produced in Cuba. Former Cuban officials living in U.S. assert that he has long skimmed profits. Castro insists his net worth is zero.