To mark 20 years since the release of the first Harry Potter book, we take a look at the reasons why J.K. Rowling isn't just a blockbuster author, but a business magician!

1. She is the biggest celebrity novelist... of all time.

You'd be hard-pressed to name another novelist who has anywhere near the international recognition as Joanne Rowling. Her personal story is as well-known as her novels' plots: that of a single mother reliant on welfare, who found herself having to write the first Harry Potter book in cafés while her infant child slept.

As proof of celebrity, Rowling also joined an elite club of novelists: those who've guest-starred in an episode of the Simpsons as themselves. Of course, unlike Neil Gaiman or Thomas Pynchon, audiences don't need Lisa Simpson to tell them who she is.

2. She redefined an author's control over the adaptations of a book

Unlike previous authors (think "Stephen King's The Lawnmower Man"), Rowling maintained unprecedented creative control over the Hollywood adaptations of Harry Potter. From her insistence on an all-British cast to the final approval on the script and director, she ensured that the Harry Potter films stayed unerringly faithful to the books -- something that wasn't commonplace before.

Thanks to her success, authors now possess much more clout in Hollywood. Bestselling novelists Suzanne Collins of The Hunger Games and Gillian Flynn's Gone Girl wrote their own screenplays. Other authors take a producer role and impose their creative visions on-set, as EL James reportedly did when butting heads with director Sam Taylor-Johnson on the set of Fifty Shades of Grey.

3. She has shown the potential of an author's subsidiary rights

It's no secret that JK Rowling is a singularly wealthy woman. On top of the royalties that come with selling over 400 million books worldwide, she's made the most out of her subsidiary rights.

In 1998, Rowling signed a rights deal with Warner Bros that encompassed both film and merchandising rights for only $500,000. Many saw this as daylight robbery, but thanks to the inexhaustible line of Harry Potter clothes, candy, board games, toys, theme parks and theatrical productions, the royalties from that partnership have made Rowling one of Britain's wealthiest women.

4. She is, technically, now the world's most successful self-publisher

When you're the world's most successful author, you can pretty much set your own terms with publishers. That's certainly what JK Rowling did when she set up Pottermore, her digital domain for all things Hogwartsy. Instead of accepting the 25 percent royalty that most authors take for ebook sales, she now keeps ALL the royalties for Harry Potter ebooks and audiobooks.

"Accio money!"

5. She refuses to rest on her laurels

So, you're 42 year-old and you've written seven of the greatest-selling books of all time. What do you do now? Less than five years after The Deathly Hallows, Rowling released The Casual Vacancy, an adult-oriented literary novel which received mixed reviews. Shifting over one million copies worldwide, her sales would have been considered stellar had her previous book not sold fifty times as many copies.

Then there's the interesting case of Robert Galbraith, the former military policeman and writer of The Cuckoo's Calling. Within months of his debut novel's release, he was outed as none other than Rowling, who had submitted the book anonymously to see whether she could publish a book without the name brand.

To inspire fellow authors, Rowling shared a number of "Robert Galbraith's" rejection letters from editors. Among other criticisms, they suggested that the author consider taking a writing course. I'm betting those editors now feel like those sales assistants from Pretty Woman.

6. She is first in line for a Nobel Prize in Tweeting, should that ever happen

Here's some sage advice. Stay on Rowling's good side when you're online. After all, she often rewards Twitter fans with a replies, retweets, or secret tidbits about the world of Harry Potter. Those on her bad side should prepare themselves for a shade-storm of epic proportions, as witnessed this year by Piers Morgan.

7. She actually walks the walk

Countless authors give their time and talent to support worthy causes, but few have had as widespread an impact as Rowling. In 2000, she founded The Volant Trust, a grant-making trust that supports women and children's charities in her adopted home of Scotland.

Rowling has since founded Lumos, an international non-profit named after the light-giving spell in the Harry Potter books. The organization works to support over 8 million displaced and disadvantaged children in orphanages worldwide.

In March of 2015, Rowling received the British Red Cross Humanity Award, joining previous recipients Sir Bob Geldof, Nelson Mandela, Archbishop Desmond Tutu.

8. She invented a whole new sport

Until flying broomsticks become a reality, Quidditch is a game that is literally impossible to play. However, this hasn't stopped legions of fans from trying.