Stars of classic film Back to the Future reunite, 33 years on

Back to the Future stars reunited 33 years after the film was released. Photo / Instagram

Back to The Future stars Michael J. Fox, Christopher Lloyd, Lea Thompson, and Thomas Wilson reunited over the weekend, 33 years after the 80s classic was released in cinemas.

The foursome appeared at a Fan Expo in Boston — where they discussed the possibility of a fourth instalment in the franchise, which birthed three films from 1985 to 1990.

"Basically, I think America is saying, 'Come on they've wrecked every other franchise with bad sequels, why not this one?' " said Wilson, who played Biff Tannen in the film.

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This was special. #backtothefuture #reunited #comiccon

A post shared by Christopher Lloyd (@mrchristopherlloyd) on Aug 11, 2018 at 10:10am PDT

The cast members and old friends shared photos from their reunion across social media — and it seems even they couldn't believe they were all together after so long.

"This was special," wrote Lloyd, 79, who played Doc Brown in the films.

"Back in 2018, even Biff made it," wrote Fox, 57, who played Marty McFly.

"Four old friends get back from the future," wrote Thompson, 57, who played McFly's mother Lorraine.

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Back in 2018, even Biff made it. @fanexpoboston @lea_thompson @tomwilsonusa #chrislloyd

A post shared by Michael J Fox (@realmikejfox) on Aug 12, 2018 at 12:03pm PDT

Speaking to news.com.au in 2015, Christopher Lloyd revealed he almost knocked back the offer to appear in the film.

"At first I was going to turn it down," he said. "I was planning to go back to New York to pursue a theatre career — that's where I started out.

Christopher Lloyd and Michael J. Fox in the original film. Photo / File

"I really had to think about the film. There was some hesitation."

The franchise was a massive success and one of the biggest pop culture phenomena of the 1980s, the three films pulling in almost a billion dollars at the box office.