While Daniel Radcliffe, Emma Watson and (admittedly to a lesser extent) Rupert Grint have gone on to have big careers since starring in the first of Harry Potter’s eight movies 15 years ago, in our hearts, they’ll always be Harry, Hermione and Ron.

The movies are so beloved that any new revelations on them are immediately intriguing, and one such revelation recently emerged through a new interview with casting director Janet Hirshenson via the Huffington Post.

Hirshenson helped in the casting of Harry Potter, the most challenging character to cast (as any fan knows), and apparently, Robin Williams advocated hard to star in the films.

He wanted to play the lovable groundskeeper Hagrid, and even went to Chris Columbus himself (director of Harry Potter and the Philosopher’s Stone & Harry Potter and the Chamber of Secrets) to state his case. However, there was an ‘only British’ rule in place.

‘Robin [Williams] had called [director Chris Columbus] because he really wanted to be in the movie, but it was a British-only edict, and once he said no to Robin, he wasn’t going to say yes to anybody else, that’s for sure,’ said the casting director. ‘It couldn’t be.’

According to Hirshenson, Robbie Coltrane was J.K. Rowling’s first choice to play Hagrid anyway. Still, it’s always fun to imagine how different these things could have worked out.

Williams attended the premiere of Harry Potter and the Philosopher's Stone when it debuted in New York. He died in August 2014.