Richest man: Sultan Haji Hassanal Bolkiah Ethnicity: Malay Industry: Oil & Gas Net Worth: $25 billion Source of Wealth: National wealth
*Note: No data on commoners' wealth and foreign sources always attribute him as as country's richest.
Cambodia
Richest man: Oknha Kith (Kit/Keith) Meng Ethnicity: Chinese-Khmer Industry: Investment, Development & Construction Net Worth: Est. $500-700 million Source of Wealth: Self Made
Indonesia
Richest man: Robert Budi Hartono (Huang Hwie Thong) Ethnicity: Chinese Industry: Cigarette Net Worth: $7 billion Source of Wealth: Self Made
Laos
Richest man: General Khamtai Siphandon Ethnicity: Lao Industry: Miscellaneous Business Activities Net Worth: Est. $800-860 million Source of Wealth: National wealth
Malaysia
Richest man: Robert Kuok Hock Nien Ethnicity: Chinese Industry: Agricultural plantation, Conglomerates/Multi-Industries Net Worth: $12 billion Source of Wealth: Self made
Singapore
Richest man: Wee Cho Yaw Ethnicity: Chinese Industry: Banking Net Worth: $3.6 billion Source of Wealth: Inherited
*Note: Singapore richest and 2nd richest man have died and fortune distributed among descendants, hence before the next official list I put the 3rd as richest.
Thailand
Richest man: Dhanin Chearavanont Ethnicity: Thai-Chinese Industry: Communication, Conglomerate/Multi-Industries Net Worth: $7 billion Source of Wealth: Inherited