Can you imagine Robin Williams as Remus Lupin in the Harry Potter franchise? It could have happened, if not for a studio role that no American actors were eligible for the casting. For years, there have been rumors of Williams lobbying to get the part, leading some fans to wonder what could have been. Ultimately, it was David Thewlis who was cast in the role and his performance can be seen in the Harry Potter movies.

In a new interview with Total Film, per Games Radar, Harry Potter and the Sorcerer's Stone director Chris Columbus spoke about the production of that first movie in the series. He officially confirmed the rumor that Robin Williams was hoping to get cast as Remus Lupin in the franchise, as it was Columbus who had to personally let Robin know he didn't have the part. It had nothing to do with Williams or his abilities as an actor, but was simply the result of an early rule that no American actors were to be cast with the goal of maintaining authenticity. As Columbus says:

"I had a conversation with Robin Williams, who wanted to play Lupin. It was very difficult for me to say 'It's all British. There's nothing I can do.'"

Previously, it had also been reported that Williams was interested in the role of Hagrid. In a 2001 interview with The New York Post, Williams didn't specifically name which characters he was interested in, but said of his desire to join the franchise: "There were a couple of parts I would have wanted to play, but there was a ban on [using] American actors. Maybe one day. Say if [Harry] goes to Yale and becomes president."

It's hard not to think about what could have been. Chris Columbus also can't help but wonder how the Severus Snape character would have turned out if Alan Rickman hadn't signed on for that role. For his part, Columbus wanted Alan Rickman as Snape, but doubted the actor would be interested after playing "such an iconic villain" in Die Hard. Fortunately, Columbus says Rickman was the "utmost professional" and took the part, and now he can't imagine anyone else playing Snape.

Robin Williams' name has gone viral in recent days because of a scene of actor Jamie Costa impersonating him going viral. While Williams is not an easy person to convincingly impersonate, Costa blew fans away with his portrayal, with many calling for the footage to result in a Robin Williams biopic. The video has amassed more than 4.5 million views in less than a week's time with an overwhelmingly positive response.

The Harry Potter movie series is based on the original novels by J.K. Rowling. Released in November 2001, the first installment of the movie series, Harry Potter and the Sorcerer's Stone, is quickly approaching its 20th anniversary. A tremendous success, it became the highest-grossing movie of the year and has since pulled in more than $1 billion in box office profits with its re-releases. It also spawned a movie series with seven sequels, culminating ten years later with Harry Potter and the Deathly Hallows - Part 2.

In September, Wizarding World hosted a global fan celebration honoring the 20th anniversary of Harry Potter and the Sorcerer's Stone. The event featured footage from the making of Harry Potter along with a special appearance from Draco Malfoy actor Tom Felton. Fans around the world celebrated the first movie and its continued effect on pop culture in the two decades since its original release in movie theaters. This news comes to us from Games Radar.