High School Musical is the all-singing, all-dancing, feel good film that most of us know the words to, whether we like to admit it or not.
So you might be surprised to know it was actually inspired by a murder.
Writer Peter Barsocchini explained how his own high school days were marred by tragedy when his father was shot dead by a business associate, and he created the musical to help him remember happier times.
And he even made a touching reference to his dad with one of the characters.
Troy's (Zac Efron's) father is his basketball coach - just like Peter's was.
"I have drawn on those times for High School Musical which has allowed me to re-experience the good times I had with my dad, who was my basketball coach," he told The Mirror in 2008.
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"In the musical, Troy's dad is the basketball coach so it allowed me to reflect on that period of my life with some joy rather than sorrow and loss."
The film came out an incredible 15 years ago, and spawned two sequels.
It introduced us to then-little known actors Zac Efron and Vanessa Hudgens, who went on to become mega-stars.
But what are the cast doing now, all these years on?
Zac Efron
Zac Efron was a relatively unknown actor when he was propelled to global fame as Troy Bolton.
He went on to play several teen heartthrob characters including a younger version of Matthew Perry in 17 Again, and also showed off his vocal skills once again in Hairspray, opposite John Travolta.
More recently, the 34-year-old has landed roles in The Greatest Showman and The Disaster Artist, and even played serial killer Ted Bundy in 2019 crime drama Extremely Wicked, Shockingly Evil and Vile.
He found the role all-consuming, and turned to meditation to help him separate himself from his murderous character and "decompress".
Zac dated his co-star Vanessa after they met on the High School Musical set, and their fans were heartbroken when they split in 2010 after five years together.
The pressure of fame hit Zac hard, and he has spoken openly about his struggle with addiction to alcohol.
Reflecting on his former lifestyle, he once told The Hollywood Reporter: "I was drinking a lot, way too much.
"It's never one specific thing. I mean, you're in your 20s, single, going through life in Hollywood, you know? Everything is thrown at you."
He has been very open about his recovery, signing up to Alcoholics Anonymous and getting "life-changing" therapy.
Now sober, the actor is an avid traveller and often shares videos of his trips and fitness tips to his 1.2 million subscribers on YouTube .
But in 2019, he contracted a serious and potentially life-threatening illness, described as a "form of typhoid or similar bacterial infection", while filming his adventure series Killing Zac Efron in Papua New Guinea.
He was treated in hospital and was reported to have made a full recovery.
Zac made headlines again earlier this year when he displayed his "new face" in a Facebook video.
His jawline looked drastically different, leading to many fans wondering if he had undergone aesthetic procedures, while others claimed it looked like he'd just recently had dental surgery.
Zac never commented on the remarks about his appearance - and he has also now grown a striking handlebar moustache for his role in The Greatest Beer Run Ever.
He has recently split from Vanessa Valladares after a ten-month romance, reportedly due to her casting in a controversial reality TV show, Byron Baes.
"He's a very good person who wanted a genuine, normal, down-to-earth partner," a source told Daily Mail Australia.
"I'm sure the final nail in the coffin was him seeing the story of her being possibly on Byron Baes and the claims that he was helping her get on it."
Vanessa Hudgens
Vanessa Hudgens' character Gabriella Montez stole the show with her epic duets alongside Troy Bolton.
After appearing in the three movies, Vanessa went onto release two studio albums, and was even a judge on So You Think You Can Dance?.
The 33-year-old has starred in hard-hitting film roles such as in Spring Breakers and Sucker Punch, and had recurring roles in TV shows including Powerless, where she played Emily Locke.
She has also appeared in more musicals such as Rent: Live and Grease: Live, the latter of which she performed in just hours after learning her father had died from cancer in 2016.
"I am so sad to say that last night my daddy, Greg passed away from stage 4 cancer. Thank you to everyone who kept him in your prayers," she tweeted.
"Tonight, I do the show in his honour."
In 2007, Vanessa was rocked by a nude photograph leak when her phone was hacked.
Speaking to Cosmopolitan in 2020, the actress admitted that it had been traumatising.
"It’s really f***ed up that people feel like they are entitled enough to share something that personal with the world," she said.
In March 2020, Vanessa landed in hot water for "insensitive" remarks she made about Covid.
In a bizarre video, she flippantly told fans: "Even if everybody gets it, like yeah, people are going to die, which is terrible... but inevitable?"
An outrage ensued, and Vanessa has since apologised and admitted it had been a "huge wake up call" about the significance of her words.
After her romance with Zac ended, Vanessa dated actor Austin Butler from 2011-2020.
This year, she confirmed she's now in a relationship with baseball player Cole Tucker.
Ashley Tisdale
Ashley Tisdale played the sassy Sharpay Evans in the HSM trilogy, but she was already well-known in the Disney world for her role in The Suite Life of Zack and Cody.
Thanks to her High School Musical success, Ashley was quickly signed and has released three albums well as forming her own TV production company, Blondie Girl Productions.
She landed a spin-off movie called Sharpay's Fabulous Adventure and has starred in Scary Movie 5 and sat on the judging panel of The Masked Dancer.
In the last few years, Ashley has stepped into the fashion world and released a clothing line with the brand Signorelli.
In September 2020, the star revealed that she was expecting her first child with husband Christopher French, and she gave birth to daughter Jupiter Iris French in March 2021.
Earlier this year, the 36-year-old addressed the "traumatic" backlash she received for having a nose job in 2007 for a deviated septum.
She told PEOPLE: "Plastic surgery wasn't culturally accepted then like it is now. When I got it done I was scrutinised, judged, and made to feel ashamed over my decision."
Corbin Bleu
Sporting star and Troy's best friend Chad Danforth was played by Corbin Bleu.
Corbin went on to star in more films including Catch That Kid and Jump In! and released two studio albums.
Amongst his many screen credentials are drama series Flight 29 Down, as well films To Write Love on Her Arms, Scary or Due, and Walk. Ride. Rodeo.
Corbin was a runner up on Season 17 of ABC's Dancing With the Stars, and has starred in several more stage musicals including Kiss Me, Kate and Godspell.
The actor married Sasha Clements in 2016, having appeared on TLC's Say Yes to the Dress together.
Now 32, he recently posted an adorable TikTok video proving he is still best friends with his High Musical co-star Monique Coleman as they beamed into the camera, having recently reunited to star in festive film A Christmas Dance Reunion.
Lucas Grabeel
Sharpay's ambitious brother Ryan Evans was played by the actor Lucas Grabeel - who is now 36.
Lucas landed several other acting gigs after his High School Musical success including playing the young Lex Luthor in Smallville.
The actor performed voiceover work from the titular role Netflix's Pinky Malinky in 2019 to a small part in Family Guy.
His other film appearances include Halloweentown High, Return to Halloweentown, Alice Upside Down, and The Adventures of Food Boy.
In recent years, Grabeel, 37, was also part of a folk-rock band called Midnight Holler.
Monique Coleman
Monique Coleman played Taylor McKessie in the High School Musical films.
Like Ashley, she also had a recurring role in The Suite Life of Zack and Cody, as well as appearances in TV show Boston Public, Gilmore Girls, Malcolm in the Middle, Married to the Kellys, and Veronica Mars.
She finished in fourth place on Dancing with the Stars in 2006, and married boyfriend Walter Jordan in 2012 on Valentine's Day.
A philanthropist, Monique was named the first ever UN Youth Champion for the International Year of Youth and went on a world tour to raise awareness of challenges facing young people.
In 2010, she launched her online talk show Gimme Mo', a show dedicated to empowering today's youth.
The 41-year-old starred in A Christmas Dance Reunion earlier this month alongside her HSM alum, Corbin.
Olesya Rulin
Kelsi Nielsen was the shy and sweet composer in High School Musical, and she was played by Russian actress Olesya Rulin.
Multi-talented Olesya is a trained ballerina who can also play the piano.
After reprising her role in the HSM sequels, Olesya also starred in the film Private Valentine: Blonde & Dangerous, alongside Jessica Simpson, as well as other titles including Flying By, Expecting Mary and Family Weekend, which starred Kristin Chenoweth.
The 35-year-old has also appeared in TV shows NCIS: Los Angeles, Powers, and Halloweentown High - alongside HSM alum Lucas Grabeel.
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