1.Coincidence?
Harry's birthday is July 31, 1980. Rowling's birthday is also July 31 – but in 1966.
2. Old but Good
The actress who played Moaning Myrtle was 37 years old when "Harry Potter and the Chamber of Secrets" was filmed. She is the oldest actress ever to play a Hogwarts student.
3. Dirty Mouth
The character of Ron Weasley originally swore a lot, but Rowling's publisher wouldn't allow her to use such language because it was inappropriate for young readers.
4.JK - Just Kidding ! (Just kidding!)
Rowling's publisher suggested she use initials rather than her given name, "Joanne Rowling," to appeal to male readers. She chose JK, borrowing the "K" from her grandmother, Kathleen. However, neither "Kathleen" nor "K" is part of her legal name.
5. Story Spoilers
Only Alan Rickman, the actor who played Professor Snape, knew his character's fate before the release of "Harry Potter and the Deathly Hallows" because Rowling told him.
6. Botanical Inspiration
Rowling has said the inspiration for the name of Harry's school in the books, "Hogwarts," may have subconsciously come from the name of a plant she saw at Kew Gardens in New York City.
7. Interesting Audition
Rupert Grint dressed up as his female drama teacher and rapped about Ron Weasley for his audition tape. His rap went something like, "Hello, my name is Rupert Grint, I hope you don't think I smell."
8. He-Who-Must-Not-Be-Named
Contrary to popular belief, the 't' at the end of Voldemort is silent. His name comes from the French word meaning "flight of death."
9. Achievement
JK Rowling based 11-year-old Hermione somewhat on herself at the same age. She even made Hermione's Patronus her favorite animal, an otter.
10. The Itchy Second Year
A lice outbreak occurred among child cast members during the filming of "Harry Potter and the Chamber of Secrets."