This year marks the 15th anniversary of the very firstHarry Potter movie, 2001’sHarry Potter and the Sorcerer’s Stone, which started the lucrative franchise and introduced the world to three little-known actors who would go on to become global superstars,Daniel Radcliffe(Harry Potter),Emma Watson(Hermione Granger) andRupert Grint(Ron Weasley). Like many big-budget blockbusters based on a wildly popular novel series, the casting has to be just right to ensure any kind of success, and it’s safe to say that the filmmakers behindHarry Potter and the Sorcerer’s Stonecertainly got the casting right. Today we have new details from casting directorJanet Hirshenson, who reveals the casting process wasn’t easy by any means, along with the unusual yet perfect reason whyDaniel Radcliffewas cast in the role of a lifetime as Harry Potter.

The Huffington Postcaught up withJanet Hirshensonto delve deeper into this historic film that kickstarted a lucrative franchise. What’s interesting is thatDaniel Radcliffehad originally taken himself out of the running to playHarry Potter, because he wanted to quit acting after starring as a younger version of the title character in the 1999 mini-seriesDavid Copperfield. ProducerDavid Heyman, who knewDaniel Radcliffe’s father, a talent agent, ran into both father and son during a night at the theater, and convinced youngDanielto audition. Here’s whatJanet Hirshensonrevealed about whyDaniel Radcliffebeat out an unspecified young actor, who was the only other top choice for the role.

“When we sat down to look at the tests. There was another guy that we kind of liked, too. There were two. (Director)Chris Columbusright away liked Daniel, but there were a couple of people who went, ‘Hmm. That other kid’s interesting.’ So we thought, ‘Let’s all go to sleep on it. We’ll come back and look at this again.’ We went back and looked at Daniel again. The other kid was terrific and very vulnerable and very Harry-looking, but besides that, Harry was going to become a very powerful kid, too. And Daniel had both sides. He was very vulnerable, but the other kid ― it was like, he [was] not going to have the balls that Daniel has, to put it that way.”

The casting director also reveals that there was “a push for the actor who didBilly Elliot,“Jamie Bell, who made his feature film debut as the title character in that 2000 film. However, he was 14 years old at the time, which was just too old since one of the casting edicts was that they cast actors who were the actual ages of the characters they’re playing. Once the filmmakers finally landed onDaniel Radcliffe,Emma WatsonandRupert Grintfor Harry, Hermione and Ron,Janet Hirshensonrevealed what happened after all three actors were told they had won their respective roles.

“After we chose, they pulled the three of them up to Chris’s office, not telling them they got the part, but they were standing there, the three of them, looking at each other, probably figuring, ‘I think we may be it.’ So they told them they had it. ‘Yay, yay, yay,’ and then they started chattering amongst themselves because they hadn’t known each other very much. Emma asked Daniel if he liked the books and he said, ‘Yeah, I like WWF better, and she did a harumph or someHermionething that was so perfect, just as herself. ‘[Gasp] WWF!’ And we just all were like, ‘Whoa, this is them.'”

Another reasonDaniel Radcliffewon the role is that he had the right color eyes, withJanet Hirshensonrevealing that a number of young actors were quite good, but they were never strongly considered because they didn’t have either blue or green eyes, to matchHarry Potter’s blue-green eyes from the books.Jamie Bellhad brown eyes, which is one of the reasons he was eliminated from contention, along with his age. One of the reasons why it was so hard for the filmmakers to castHarry Potter, and all of the other characters for that matter, is the producers had a strict rule of hiring only British actors to play these characters. In fact, the late comedic legendRobin Williamswanted to play Hagrid so badly he called directorChris Columbusto ask for the role, which ended up going to authorJ.K. Rowling’s first choice for the role,Robbie Coltrane. Here’s what the casting director had to say aboutRobin Williamsasking for the Hagrid role.

“Robin Williamshad called [directorChris Columbus] because he really wanted to be in the movie, but it was a British-only edict, and once he said no toRobin, he wasn’t going to say yes to anybody else, that’s for sure. It couldn’t be.”

Harry Potter and the Sorcerer’s Stoneopened in November 2001, taking in $317.5 million domestic and $974.8 million worldwide, figures which are the second best in the franchise behind only the final movie,Harry Potter and the Deathly Hallows - Part 2($381 million domestic, $1.3 billion worldwide). The franchise continued this year with the spin-offFantastic Beasts and Where to Find Them, which is set 70 years before Harry, Hermione and Ron first set foot in Hogwarts. The franchise also continued on the London West End stage with the new playHarry Potter and the Cursed Child, which will debut on Broadway in 2018.