The Harry Potter Hallowe'en spoof was a great success.
And Simpson's creator Matt Groening is a huge fan of Harry Potter anyway.
But now, he's gone one step further letting JK playing herself.
When Newsround first told him a few years back that JK loved The Simpsons too and asked if he'd include some Potter references, he was very pleased.
"Wow, I am honoured, my kids have devoured all of the books. No doubt we'll do some Harry Potter references."
That promise has now come true. J K Rowling has recorded her lines, but the animation takes a bit of time and has not yet been completed. There's no word yet on when it'll air in the UK.