Saudi Arabia's Prince Alwaleed bin Talal ranks #26 on the most recent (March 2011) Forbes list of the world's richest people. According to Forbes, the prince, who is a nephew of the Saudi king, has a net worth of $19.6 billion. No other royals made the top 100 list (please let me know if you spot one I missed).
How can you forget the king of Thailand??? His net worth is >30billions. Read the Forbe's Richest Royal…
You will see that the King is not included on Forbes' list of top 100 billionaires, although he is on the 2010 richest royals list. The Forbes website is difficult to navigate and I can't find an explanation there on how they drew up their Richest Royals list, but I would guess Forbes judges monarchs' worth differently than it does individual worth, perhaps because not all the money is held in the monarch's own name.