The only time we've seen another actor play Harry Potter was when Harry and the gang took Polyjuice Potion in Chamber of Secrets. We didn't enjoy it for obvious reasons.

But the reality of the situation is that another actor could have played the famous wizard. We couldn't imagine it any more than imagining someone else playing Luke Skywalker, Frodo Baggins, or Captain America. Once someone's made their mark on those heroic characters, that's it; no one else can play them. If someone tried, it'd be tough to reset society's brains to be able to see anyone else. We'd need M.I.B.'s Neuralyzer to wipe our memories clean.

When they were casting Harry, the director, casting director, and J.K. Rowling went through thousands of possible Harrys and almost gave up in the process. They landed on one possible boy, but they threw that idea out the window when a chance sighting of one obscure British boy graced their screens. But he proved harder to get than all the rest.

Here's how Daniel Radcliffe almost wasn't Harry Potter and how his parents almost threw a wrench in the works.

Radcliffe Made An Impression...On Two Occasions

Another casting director had already started working on Harry Potter and the Sorcerer's Stone when Janet Hirshenson arrived on the scene. By then, the parts of Ron and Hermione were already narrowed down, but they still had no idea about Harry.

Earlier in pre-production, Steve Spielberg was set to direct, and he wanted Haley Joel Osment, the Oscar-nominated child star of The Sixth Sense. He quit when that idea was shot down by Rowling, who wanted unknown British children to be cast.

Related: Daniel Radcliffe Got Caught With A Battery Power Pack While Shooting Harry Potter

The new director, Chris Columbus, screen-tested another American boy named Liam Aiken, who he'd previously worked with on Stepmom. But as before, it had to be an unknown British boy, and in fact, the "only British" rule applied to everyone who was cast in the film. So that meant not even Robin Williams could play Hagrid.

There was also a long list of things they had to check off for getting the right Harry. He had to be the right age and have the right eye color.

It turns out Columbus actually already knew who he wanted to be Harry Potter early on in the casting process. When he randomly popped in a VHS of BBC's David Copperfield, he knew the little boy playing a younger Copperfield would be perfect. But by that point, Radcliffe apparently quit acting after doing that BBC production and his first film, The Tailor of Panama.

It wasn't until one month before they were supposed to start shooting that the film's producer, David Heyman, had a chance run-in with Radcliffe and his family.

Related: Does Daniel Radcliffe Regret Starring In The Harry Potter Franchise?

At a London theater production of Stones in His Pockets, Heyman bumped into Radcliffe and his parents, Alan and Marcia, who had both been child actors like their son. Alan is a literary agent, and Marcia is a casting agent. They both knew Heyman and introduced him to a young Radcliffe.

Heyman was struct by the little boy and couldn't keep his attention away from him. "It was a very good, award-winning play — and it was completely forgettable for me. All I was thinking about was the boy sitting in the row behind me — Daniel Radcliffe. He had these big blue eyes, a deep curiosity, a real stillness, and composure — he was an old soul in a young body. When I met him, he was incredibly generous of spirit, warm, friendly, and open. He wanted to please in the most unassuming of ways. What was also evident was an inherent decency, which he still has today," Heyman told Entertainment Weekly.

Heyman knew Radcliffe was his Harry Potter, sitting in that play, but he didn't know that he'd have to do a lot of negotiating to get him to say yes.

His Parents Didn't Want Him To Audition

Heyman went up to Radcliffe during the interval and asked him if he wanted to audition. Alan Radcliffe said maybe.

"He saw it as a sign. Like I don't believe in that sort of stuff particularly, but they took it as a sign that it was somehow meant to be, and so they let me audition," Radcliffe said. But after a hard think about it, they thought maybe it wasn't a good decision.

"They went to my parents, and, at the time, the deal was to sign on for – I think – six films, all to be done in L.A., and my mum and dad simply said, 'That’s too much disruption to his life. That’s not gonna happen,'" Radcliffe told THR.

Related: Here's What Daniel Radcliffe Has Said About Playing Harry Potter

"I didn’t know any of that had gone on. And then, maybe three, four months down the line, the deal had changed, and it was gonna be to shoot two films, and they’d both be done in England, and so they said, 'Okay.'"

After several auditions and screen tests, they locked in Rupert Grint and Emma Watson as Ron and Hermione, but there was still Harry.

"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," Hirshenson said.

They chose Radcliffe after a long hard decision, and as we all know, they did film in England. But the franchise wasn't just two films; it turned into eight. Wonder if the Radcliffe's ever felt annoyed that they were lied to about that deal. In the end, though, their decision to let their son audition and take the role was probably one of the best in their lives. Radcliffe's parents had his back through it all, just like Harry's had his looking over him too. Always.

Next: Helena Bonham Carter Almost Wasn't Cast As Bellatrix Lestrange In 'Harry Potter', And Here's Why