Duncan Sheik, the Tony- and Grammy-winning singer-songwriter who composed the music for “Spring Awakening,” has passed away.

He was 56.

Sheik died Thursday night, as stated in a post on his Instagram page.

“The world has lost a singular talent, and a deeply influential voice in music and theater,” the post reads.

“His musical legacy will continue to inspire generations to come.”

Sheik was best known for his enduring radio hit "Barely Breathing" when he turned his attention to Broadway with "Spring Awakening," producing a boundary-pushing show that set teenage angst to music.

"With the exception of our director, we are all, to some extent, Broadway outsiders.

We wanted to shake things up a bit.

And we simply set out to create this genuinely remarkable piece of theater," Sheik said in 2007, as the show swept Tony nominations.

Sheik also wrote musicals based on “American Psycho” and “Alice in Wonderland,” and “Barely Breathing” stayed on the Billboard Hot 100 for 55 weeks, peaking at No. 16.

However, he was probably best known for “Spring Awakening,” which ran for over 860 performances on Broadway starting in 2006.

“His profound emotion and his joy brought us so much beauty,” playwright and actor Eisa Davis wrote.

“Duncan, thank you for your friendship and for the sublime music.”

The musical — adapted from a 19th-century play by the German playwright Frank Wedekind, with music by Sheik and lyrics by the playwright Steven Sater — is unflinching in its depictions of incest, abortion and suicide.

It is intended in part as a warning that adolescents need sound information about sex to avoid tragic mistakes.

"I don't wish to show any disrespect toward more traditional theater composers," he told the Los Angeles Times in 2015.

"I hold Stephen Sondheim in high regard.

Nevertheless, it is my mission to ensure that the theater is attuned to what the rest of the world is listening to."

Sheik and Sater, both practicing Buddhists, first encountered one another while chanting.

They were in the midst of collaborating on Sheik’s third album, “Phantom Moon,” when Sater happened to mention that he was engaged in work on a new production.

Neither of them had ever written a musical before.

“I told Steven, ‘I’m happy to do this musical, but I only want to do it if the music in the play is the kind that I and my peers can get behind stylistically and relate to and enjoy,’” Sheik said in 2006.

They made a pact: they would retain the provincial, 19th-century German setting, yet with, as Sater put it, “the characters breaking into pop-contemporary when they sing.”

“Spring Awakening” garnered eight Tony Awards, among them best musical, in addition to the Grammy for best musical show album.

“Sheik’s music, with its simple, restrained orchestrations and the rich, sweeping pull of its seductive choruses, captures the show’s shadowy atmosphere of longing, its excitement edging into fear, and its joy followed by a hint of despair,” The New York Times said in its review.

The show is cherished within the musical theater community for its pioneering strides in staging and content, standing alongside the likes of “Rent” and “Hamilton.”

It made its return to Broadway in 2015 in a well-received production by Deaf West Theatre.

An off-Broadway rendition is scheduled to premiere this fall, as is his musical “Memoirs of Amorous Gentlemen,” adapted from Moyoco Anno’s manga of the same name.

The cast of the original show included many breakthrough actors like Jonathan Groff, Lea Michele, Lilli Cooper, Jennifer Damiano, Gideon Glick, John Gallagher Jr., Lauren Pritchard and Krysta Rodriguez, who have each gone on to fame in TV, film and stage.

Groff would go on to earn a Tony with “Merrily We Roll Along,” and Michele became a superstar with “Glee.”

Sheik then drew on the music he heard after getting past the velvet ropes of fashionable late-1980s Manhattan clubs for a Broadway adaptation of Bret Easton Ellis's novel "American Psycho."

The 1991 novel — later adapted into a 2000 film starring Christian Bale — chronicles Patrick Bateman, a homicidal New York yuppie whose obsession with high-end clothes and beauty products persists even as he slashes his way through Manhattan.

Sheik, who also provided the lyrics, recalled that, as a Brown University student, she had gotten only halfway through the book before throwing it across the room.

For one particularly notable track, “You Are What You Wear,” he approached former girlfriends with a question: what did you genuinely favour wearing in the late ’80s?

He incorporated their responses into the song about high fashion: “Chanel, Gaultier, or Giorgio Armani/Moschino, Alaïa, or Norma Kamali/Should I rock/The Betsey Johnson/Or stick with classic/Comme des Garçons?”

“Duncan is genuinely a genius and an intellectual, and he brings to the stage something that is both uniquely his own and, crucially, typical of this period,” producer Jesse Singer said at the time.

Because Bateman, played onstage by Benjamin Walker, fancies himself something of a music critic — spewing mostly inane ruminations about Phil Collins and Huey Lewis and the News — Sheik also peppered his score with sly reworkings of “In the Air Tonight” and “Hip to Be Square.”

“There’s definitely an art to writing a song that works on one level as a pop song while also having to tell a story and keep an audience engaged with a larger narrative arc,” Sheik said in 2013.

“When you’re writing a song for the theater, it has to accomplish all this other stuff.

It has to work in tandem with all these other agendas and creative impulses.”

The show, directed by Rupert Goold and with a story by Roberto Aguirre-Sacasa, premiered in London in 2013.

When it moved to Broadway in 2016, it flopped, lasting fewer than 90 performances.

"We were all somewhat worried that it might be too violent for people and might seem too misogynistic," Sheik said on the eve of the opening.

"But in fact, the truth is that this piece is a critique of a particular way of thinking about things.

So in truth it's better to go all-in."

Having divided his formative years between South Carolina and New Jersey, Sheik took up the guitar in childhood and acquired his first synthesizer at the age of 12.

He drew heavily on the influence of Talk Talk, David Sylvian and Nick Drake.

His self-titled debut album saw release in 1996, and Rolling Stone awarded it a four-star review, describing it as “a defiant debut — beautiful and benevolent of spirit.”

“Barely Breathing,” a track from that album, garnered a nomination for best pop vocal performance in 1998 and would endure through television series such as “Glee” and “Girls.”

Other projects include "Whisper House," an album and musical — a ghost story that was staged in 2010 at the Old Globe Theatre in San Diego — and "Legerdemain," an album that explored the tension between art and commerce.

His most recent album was 2022's "Claptrap."

Yet for someone who had once been a complete stranger to Broadway, he told AP in 2016 that he had a sense of mission.

“I feel as though it has become something of my personal mission to draw in individuals who might not ordinarily attend musical theater productions and persuade them to come and experience a piece of musical theater,” he said.

He is survived by his parents, his wife, Nora Ariffin, and a daughter, Ines.