Perhaps hard to fathom now, but in the 1970's, Henry Winkler's Happy Days character Fonzie was just as big, or maybe even bigger than superstar John Travolta. And it was Henry Winkler who was initially sought for the role of Danny Zuko in the big screen adaption of Grease. But he eventually turned down the role for one very personal reason.

As Fox prepares to unleash Grease: Live later this month, Vanity Fair has an expose on how the original 1978 movie made it's way to the big screen from the stage. And it's one musical that has certainly stood the test of time in various different formats and mediums. But would the movie be remembered as the classic it is had Henry Winkler decided to stay on board?

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Henry Winkler isn't the only big name that decided against appearing in the movie at the last minute. A number of superstar actors were considered for key roles. And probably the biggest of these actors was Elvis Presley. He is said to have been in the running to play a cameo as Teen Angel, the role that eventually went to other 50s heartthrob Frankie Avalon. Elvis Presley turned down the role, and as it turns out, he actually passed away while the film was in the midst of production. Had he signed on, his death wouldn't have caused too many complications for the movie, as it was just one scene that required very little screen time.

As for Henry Winkler, he had a much more honest reason for turning down the role of Danny Zuko. He was already well known for playing a 50s greaser on TV every week. While he heavily considered taking on the musical, he ultimately decided he didn't want to be typecast. In turn, Henry Winkler was one of the few actors who stayed with Happy Days through its epic 11 season run, and his feature film work was few and far between.

What do you think of these possible changes to the cast? Is it hard to image The Fonz playing a role made so iconic by John Travolta? And would the character of Teen Angel have been a weird, eerie send off for one of Rock 'n Roll's biggest legends just before his death? We'll get to see a whole new cast take on these iconic characters when Grease: Live airs January 31 with Aaron Tveit in the role of Danny Zuko and Boys II Men collectively sharing the role of Teen Angel.