Emma Watson gives J.K. Rowling a 'sexy and scary' throwback photo for her birthday

Bryan Alexander

July 31 is a big day for Harry Potter fans around the world.

It's author J.K. Rowling's birthday, she turned 54 today. Further it's the birthday of the boy wizard himself, Harry Potter. In Rowling's fictional "Harry Potter" world, her beloved boy wizard was born on July 31, 1980.

That would make him 39 this year.

Emma Watson, better known as Hermione Granger, sent out a tweet Wednesday featuring a "sexy and scary" throwback costume photo.

Rowling donned a horned mask, Watson was dressed as Wonder Woman and Evanna Lynch (Luna Lovegood) wore "the most perfect cat" outfit in the shot.

"You smashed this," Watson wrote, wishing Rowling "Happy Birthday!!!"

Other fans paid their own respects.

This article originally appeared on USA TODAY: Harry Potter birthday: Emma Watson sends J.K. Rowling 'sexy' photo