As fans wait for the fifth book in the Potter series, JK is counting the cash, and is now worth £226m, £26m more than Madonna.
The US music queen is at number 161 in the Sunday Times list of Britain's 1,000 richest people, 14 places behind the best selling kid's author.
Robbie and Becks tied for 962nd
Swing king Robbie Williams is also on the list, but way down at the bottom in 962nd with £35m, the same amount as Posh and Becks' family fortune.
That's the Duke of Westminster, who has a mind boggling £4.7bn (£4,700m) stashed in the bank, £300m more than he had last year.
Most of his fortune comes from houses and property he owns around the country, but especially a big chunk of land in one of the most expensive parts of London.