The casting of 'Grease' was almost terrifyingly wrong.

A recent, shocking report by Vanity Fair has revealed that Olivia Newton-John and John Travolta were not originally intended to be the stars of the beloved movie Grease (gasp!).

Apparently, the iconic roles of Sandy and Danny nearly went to Carrie Fisher and Henry Winkler.

Who are those people, I hear you ask? I’ll tell you who they are: actors who should never have been in Grease, let’s not talk about it anymore because it’s giving me heart palpitations.

Ok, fine, I’ll tell you who they really are. Winkler was best known for his role as Fonzie in 7os sitcom Happy Days, and Carrie Fisher played Princess Leia in the original Star Wars movies.

While Winkler, turned down the role of Danny because he didn’t want to be ‘typecast’, director Randall Kleiser was unsure about Fisher’s singing and dancing abilities and decided to keep looking.

It seems Travolta was barely interested in the role at first, putting off production so he could finish making Saturday Night Fever.

Newton-John, too, was concerned about the impact Grease might have on her career.

“I was very anxious about making another film, because my music career was going well,” she told Vanity Fair.

“I did not want to mess it up by doing another movie that wasn’t good.”

She also had doubts about the quality of her American accent, and whether she was too old (at 29) to start alongside Travolta (22).

Luckily, the directors were happy to make Newton-John’s character Australian – and as for looking old, well, let’s just rewatch this dance scene again.

(Deep breaths).

The on-film chemistry between Newton-John and Travolta was second to none, partially because Travolta wanted her in on the project from the get go.

“She had a brilliant voice, and I didn’t think there could be any more correct person for Sandy in the universe,” Travolta told Vanity Fair.

“I never let up on it. I insisted that she be met and that we cast her.”

And thank God you did, John. Thank God you did.