Which big stars turned down the leads for 'Grease?'

Olivia Newton-John and John Travolta in "Grease." (The Associated Press)

"Grease" stars John Travolta and Olivia Newton-John turned their leading roles of Danny and Sandy into iconic characters, but they weren't the only ones who were considered for those parts.

While it's hard to imagine anyone else in the role of Sandy, Marie Osmond actually turned the gig down, according to Vanity Fair contributing editor, Michael Callahan.

WATCH: Your First Look at Julianne Hough & Vanessa Hudgens Revamping a Classic in 'Grease: Live'

"She didn't foresee how big a turn Sandy was going to take at the end in that spandex outfit, and that just wasn't her image," Callahan told ET.

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Linda Ronstadt and Carrie Fisher were also considered for Sandy, but as Travolta reminded ET in 1998, "every guy in the world wants Olivia Newton-John as their girlfriend."

Travolta was signed on to the film prior to Newton-John’s casting. He might seem like the obvious choice to play Danny now, but at the time, producers had their sights set on another popular actor.

"Henry Winkler dropped out, because he didn't want to be typecast forever as Fonzie," Callahan said.

Of course, the final cast proved a winning combination, as "Grease" went on to be the No. 1 grossing movie of 1978.

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"I think we're very lucky," Newton-John told ET in 1983. "It could have been somebody else and it might not have been the same."

On Sunday, Jan. 31, Fox will reimagine the seminal musical with a live, one-night production featuring Julianne Hough as Sandy, Broadway veteran Aaron Tveit as Danny, Vanessa Hudgens as Rizzo, Carly Rae Jepsen as Frenchy, Kether Donohue as Jan, David Del Rio as Putzie, Carlos PenaVega as Kenickie and Keke Palmer as Marty.