Yes, we hate to break it to you, but the movie that will forever symbolize youth and coolness is officially middle aged this year.
While we still find the teen romance electrifyin', we wondered what the cast was up to after all these years. Here's what we found:
John Travolta - Danny
While he's not the only successful cast member from the movie, you're probably most familiar with Travolta's career after Grease. He's starred in a long list of hit films, including Pulp Fiction and Get Shorty, and even played Robert Shapiro on the TV show The People Versus O.J. Simpson.
After 40 years, Travolta's career shows no signs of slowing down.
Jeff Conaway - Kenickie
Sadly, Conaway is one of the three actors on this list who have passed away since their role in Grease. He was a regular actor on Taxi, Wizards and Warriors, The Bold and the Beautiful, and Babylon 5 after Grease.
Conaway died after catching pneumonia in 2011.
Barry Pearl - Doody
If you remember Doody, it's probably for the scene where he mooned the audience. Pearl (along with Travolta) was one of the original actors from the stage version of Grease.
He went on to have parts on Baywatch, House, and Criminal Minds, and also appeared on Fox's Grease: Live show.
Stockard Channing - Rizzo
At 33 years old, Channing was the oldest "teenager" in the cast, and she also had one of the most successful post-Grease careers.
Channing was Oscar-nominated for Six Degrees of Seperation, and had regular roles on The West Wing and The Good Wife. Channing is still acting today, but mainly on Broadway.
Lorenzo Lamas - Tom Chisum
Lamas made an impression with his small role as a football player who had eyes for Sandy. He continued his career with roles on TV shows like Falcon Crest, The Bold and the Beautiful, and Renegade. Lately he's been doing voice work, including on Disney's Phineas and Ferb.
Susan Buckner - Patty Simcox
Buckner's part as the geeky blonde with the cat eye glasses turned out to be her most famous role. She had small parts on shows like The Love Boat, but hasn't been in a movie since 1981.
Michael Tucci - Sonny
After Grease, this T-Bird appeared on shows like The Paper Chase, It's Gary Shandling's Show, and Diagnosis: Murder. But his career is still going strong, with a new movie role this year.
Jamie Donnelly - Jan
This Pink Lady has changed her signature look over the years, but she's never stopped acting. You can see her in movies like Can't Hardly Wait, Cyrus, and the Johnny Depp gangster movie Black Mass.
Didi Conn - Frenchy
The beauty school dropout isn't dying her hair pink these days, but she's still very connected to her famous character. She was one of the few cast members to come back for Grease 2.
Since then, Conn has appeared on shows like Law and Order and has raised awareness for autism - which her son Daniel was diagnosed with.
She also had a cameo in Fox's Grease: Live show, and bonded with singer Carly Ray Jepsen, who played Frenchy in that production.
Kelly Ward - Putzie
After Grease, Ward noticed his offers for acting roles were few and far between, but he's still doing just fine. Ward transitioned to become a dialogue director, and helps make animated shows like Disney's The Lion Guard.
Dinah Manoff - Marty
She played Sonny's girlfriend in the movie, but that was probably the last big role you remember her from. After taking parts in Child's Play and Ordinary People, Manoff stepped out of the spotlight in 2008.
Annette Charles - Cha Cha
She was Danny's ex-girlfriend and the best dancer at St. Bernadette's (with the worst reputation). While Charles had small parts in TV shows like Magnum P.I. and The Incredible Hulk, Grease was her last big role.
Charles died of brain cancer in 2011.
Eddie Deezen - Eugene
Deezen was picture-perfect as the geeky Eugene, who was one of the few characters to return in Grease 2. Since then, he's showed up in a handful of Hollywood movies - like Wargames - but mainly he does voice acting these days.
Dennis C. Stewart - Leo
With his distinctive pockmarked face, Stewart was perfect as the movie's bad guy, and the leader of the Scorpions. He returned to play another bad guy in Grease 2, Balmudo.
Stewart's career after Grease was short, but he had small roles on great TV shows like The A-Team and Moonlighting. Stewart died from AIDS in 1994.
Olivia Newton-John - Sandy
The Australian actress's musical career took off after Grease, when she released hit songs like "Physical," which won her a 1981 Grammy. John has been touring ever since, including her Vegas residency from 2014 to 2016.
She even reunited with John Travolta for an album of duets, called This Christmas.
While she hasn't focused on her acting career as much, she still had memorable parts in Xanadu and Two of a Kind, which also starred Travolta. In recent years, she also faced down a scary cancer diagnosis.
Who was your favorite character?