Through his leading role in Grease, John Travolta was catapulted to international stardom at quite a young age. Based on the 1971 musical of the same name, the 1978 musical rom-com movie Grease saw John Travolta and Olivia Newton-John as the teenage couple Danny Zuko and Sandy Olsson. The two, who first shared a summer romance, reunited at their high school, where Danny was revealed to be the leader of the T-Birds greaser gang. Grease was a critical and commercial success, even earning the spot for the highest-grossing musical film of 1978. With its best-selling Oscar-nominated soundtrack and the performance of its cast, the film cemented its place as a cult classic.

Considered by many as one of the best musical films of all time, Grease launched a franchise. Its critically-hated sequel Grease 2, starring ​Maxwell Caulfield and Michelle Pfeiffer, was released just four years later. A Grease-inspired Paramount+ series titled Grease: Rise of the Pink Ladies is set to debut in late 2022, while the prequel film Summer Lovin’ is reportedly in production. Grease’s legacy came as no surprise; after all, it gained generally positive reviews from critics at the time. They pointed out how the musical’s energetic choreography and infectious songs provided a genuine showstopper deserving of applause. Meanwhile, they also recognized the magnetic chemistry between Travolta and Newton-John, who were convincing enough despite portraying roles younger than their actual ages.

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Because of labor laws, it was easier for films to cast actors over the age of 18 as high school students. Because these actors were already professionals, they were allowed to work longer hours. Moreover, these older actors already had the experience needed to portray a teenager in a stylized camp movie like Grease, which ended with Sandy’s transformation and a flying car. In fact, when the musical hit was filmed in 1977, leading man John Travolta, who was born on February 18, 1954, was just 23. His character, Danny Zuko, was supposed to be an 18-year-old senior at Rydell High School. For this age gap to be believable, Grease director Randal Kleiser revealed that he administered a crow’s feet test on the cast. Those with visible crow’s feet around their eyes would not acceptably look like teenagers, after all, but that was still unavoidable, considering that Travolta was actually one of the younger principal cast members.

How Old Were Olivia Newton-John & Other Cast Members In Grease?

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Olivia Newton-John, who starred opposite Travolta in Grease, was years older than her character and her leading man. Her character Sandy Olsson, who was theorized to be dead throughout the film, was almost the same age as Danny. However, Newton-John, born on September 26, 1948, was already 29 years old when she filmed the film. Prior to her starring role in Grease, she had almost no acting experience, but she already established her career as a Grammy-winning country and pop singer. Because Newton-John was concerned about looking considerably older than Travolta, Grease’s cinematographer Bill Butler solved this issue by filming her with soft lenses.

In Grease, the Pink Ladies was led by Betty Rizzo; the 18-year-old was played by the oldest among the main cast, then-33-year-old Stockard Channing. Marty, who was forcing herself to act mature throughout the film despite only being 17 years old, was played by Dinah Manoff in her feature film debut. The actress was only 21 at the time, making her high school portrayal quite a realistic one. Pink-haired Frenchy, who disappeared halfway through Grease 2, was portrayed by 26-year-old Didi Conn in the original film. Meanwhile, pigtail-wearing Jan was 30-year-old Jamie Donnelly in real life.

On the other hand, Danny Zuko was supported by his reliable T-Birds gang. Kenickie, who served as second-in-command and Betty’s boyfriend, was also 18 in the movie. He was played by Jeff Conaway, who was eight years older than his character at the time of filming; the actor died in 2011 at the age of 60. The 18-year-old jester, Sonny LaTierri, was played by Michael Tucci. He was the second-oldest cast member, joining the film at 31 years old. Meanwhile, Barry Pearl, who embodied the group’s comic relief Doody, was actually 27 when he got the role. Lastly, clumsy Putzie was brought to life by Kelly Ward, the youngest in the pack; he was only 20 when he was cast in the hit musical Grease.

NEXT: Why Grease 3 Didn't Happen