Veteran actor Marlon Brando refused to do one thing while making The Godfather, which has left fans stunned.

The Hollywood movie is regarded as one of the best films of all time by fans, though the difficulties behind the scenes are well known. One slight struggle came from Brando, with his refusal to do one thing on set leaving fans split on his final performance.

A post to the r/TodayILearned Reddit page has fans discussing Brando's career in Hollywood, with the star just 42 when he appeared as Don Corleone in Francis Ford Coppola's classic mob film.

It is not the first time Brando has refused to do something on set, with a similar practice used for his role in Superman just six years after the release of The Godfather.

Fans are split on whether his major refusal worked to his favour, as some suggest he was "disillusioned" with the cinematic process, while others hailed it as bringing out a "spontaneous" best in his work.

A post to the r/TodayILearned subreddit reads: "During the filming of The Godfather, Marlon Brando refused to memorise his lines, and would read them off cards attached anywhere from trees in the background to fellow actors."

Fans were stunned to realise Brando was not learning his lines but reading them from placards scattered across the set. One user wrote: "Everyone here hating on this without understanding it. People in conversation haven't memorized lines. They fumble around for words. They misspeak etc.

"Brando didn't memorise lines so they his dialogue would better resemble this natural cadence. And it's a big part of his unique character. His dialogue is stulting and stumbling. It adds significantly to the authenticity of his performance."

Another suggested Brando would have done well to retire after his performance in A Streetcar Named Desire. They wrote: "Brando seems to have peaked too early and then became disillusioned with Hollywood and filmmaking.

"He probably would’ve been happier retiring into basically anything else after Streetcar. With so much life still ahead of him he could’ve had a whole other career with decades to spare."

Another disagreed, adding: "I don't think it was disillusionment with Hollywood really, because he ended up having contempt for acting as a whole."

Similar stories from the set of Superman were also shared, as Brando had reportedly argued he should not know what his character is going to say, to keep it a surprise for his performance and for the viewers in the cinema.

One fan explained: "He did the same in Superman and I remember a documentary about it from back in the vertical-load VHS days where his excuse was that it made his delivery more spontaneous.

"But I can't help observing that Brando managed to ascend to a level of greatness where he no longer had to learn his lines, which I have a feeling a lot of actors would like to enjoy, if only they had the pull that Brando had. I wonder how far back it went in his career."