Harry Potter

The Doctor had read the Harry Potter series of novels, and cried upon reading the ending of the final book. Martha Jones also knew the books and suggested Potter's magic word "expelliarmus" to William Shakespeare to help defeat the Carrionites. The suggestion worked. (DW: The Shakespeare Code) Donna Noble jokingly referred to a centaur she met as Firenze - the name of one of the centaurs in the Potter universe (BBC Audio: Pest Control). A copy of Harry Potter and the Philosopher's stone can be seen in a display case on Platform One.

In the Eighth Doctor Novel, The Gallifrey Chronicles written in 2005, Rachel picks up a copy of the last Harry Potter book in the TARDIS, before replacing it next to its "ten other sequels." Clearly the author had no idea how many books would be in the completed series (7).

Trivia

 * In 2005, Russell T Davies asked Harry Potter's creator J.K. Rowling if she would write for Doctor Who. She refused, saying that she was "was amused by the suggestion but simply doesn't have the time." She was writing the sixth Harry Potter novel at the time.


 * In The Christmas Invasion, a Hogwarts-style uniform briefly appears as the Doctor considers what clothes to wear in his new incarnation.


 * The Shakespeare Code, in which The Doctor references reading the final book, was broadcast before the book was published, during a period of intense anticipation for its release. The Doctor doesn't mention the book's title, as it had not been revealed by the time the episode began filming.


 * According to his 2008 autobiography A Writer's Tale, Russell T Davies considered basing the 2008 Christmas special around an appearance by Rowling.


 * Harry Potter star, Daniel Radcliffe, was a name thrown out by Russell T. Davies to play The Eleventh Doctor.

Doctor Who actors who have been in Harry Potter

 * John Cleese played Headless Nick in the films
 * Roger Lloyd Pack played Barty Crouch Snr. in the films
 * David Tennant played Barty Crouch Jr. in the films