J.K. Rowling's books have sold than 300 million copies. Picture / Reuters

J.K. Rowling's books have sold than 300 million copies. Picture / Reuters

Her picture hangs in Britain's National Portrait Gallery, her books have sold more than 300 million copies and a prehistoric dinosaur has been named after her Hogwart's creation.

And when it comes down to hard cash, the Harry Potter author J K Rowling is not doing too badly either.

She has been named the celebrity world's ninth-highest earner, with a fortune that increases by £77 ($230) a minute - more than £100,000 ($300,000) a day.

Rowling, who is writing the seventh and final book in the series, is the only non-American within the top ten highest-earning celebrities, according to the US business magazine Forbes.

Last year alone she earned £41m ($122m).

The penultimate novel in her series, Harry Potter and the Half-Blood Prince, was the best-selling novel of 2005 in the United States, shifting more than 7.2m copies.

Hannah Clark, of Forbes, said: "While celebrities grab headlines, it is rarely actors who make money. If you want to keep making money in the long term, you need a winning franchise and J K Rowling is proof of that."

The last three volumes in the series have all been the fastest-selling books in history, with bookshops opening at midnight, such was the demand for the next installment of wizardry.

They have grossed more in their opening 24 hours than many blockbuster films.

Rowling has suggested that, when she finishes the Potter series, she may write novels under an alternative name.

The only other novelist among the celebrities was the author of the best-selling The Da Vinci Code, Dan Brown.

The film-maker Steven Spielberg, whose recent projects include War of the Worlds and Munich, topped the celebrity rich list.

He is estimated to have made £180m ($539m) in 2005, or £342 ($1024) every minute.

The American radio DJ Howard Stern was second, earning £163m ($488m), and the Star Wars director George Lucas third, with a fortune of £127m ($380m) last year, the magazine calculated.

The creator of the television series "about nothing", Jerry Seinfeld, was in fifth place in the list, despite the sitcom ending in 1998.

His £54m ($161m) income for last year - or £103 per minute - was boosted by the release of DVD box sets of the series.