5. Alan Richman was handpicked by J.K for the role of Snape

J. K. Rowling wanted an authentically British cast, with a few exceptions. The author was hands-on in the casting of the film, handpicking Alan Rickman for the role of Severus Snape. Rickman received special instructions from the author as to his character, providing him with vital details of his back story that were not revealed until the final novel years later.