Stephen Sondheim, the composer and lyricist behind such mainstays of American culture as Sweeney Todd, Company and Sunday in the Park with George, died Friday at age 91.

Keith Lockhart, conductor of the Boston Pops, said in an email to GBH News that American musical theater has lost a giant.

“I suppose I was always hoping, hoping against hope as he grew inevitably older, that he had one more great work of art left in him to share with the world,” Lockhart wrote in an email to GBH News. “The fact that our minds and hearts now won’t be challenged by another Sondheim work is a difficult one to come to grips with.”

While Sondheim is synonymous with New York — it is both his birthplace and home to his many Broadway hits — the Tony, Grammy, Pulitzer Prize and Academy Award winner also had ties to Boston. His works found homes, some even their first homes, on Boston’s stages, and his reach extended into the hearts and minds of the city’s artists.

“Much of Sondheim’s music found its way onto the Pops’ stage over the years and, notably, his most famous song, ‘Send in the Clowns,’ was written in a hotel suite in Boston, during out-of-town tryouts for A Little Night Music,” writes Lockhart.

Sondheim’s relationship with the region began in the late ’40s, when he went to Williams College to study music and composition. Years later, Sondheim took advantage of Boston’s theater scene where he gave his musicals a trial run. In 1970, Company had its pre-Broadway tryout at Boston’s own Schubert Theatre. One year later, the Colonial Theatre was a pre-Broadway venue for Follies, and other works premiered on Boston stages before moving on to Broadway.

Spiro Veloudos, producing artistic director emeritus at The Lyric Stage Company of Boston, has directed nearly all of Sondheim’s major works.

“Sondheim affected me the same way Shakespeare affected me,” Veloudos said. “They have a very unique view on life, and that’s what drew me to Sondheim. His work was like an onion, peel it back and there’s another layer to it.

“Sondheim described himself as more of a playwright than composer,” Veloudos continued. “It’s true: each song is a play onto itself.”

Sondheim’s reach goes beyond the main stage, influencing artists in Boston’s fringe theater scene. Provincetown-based Ryan Landry is the founder of the Gold Dust Orphans, a Vaudeville-inspired troupe known for its theatrical mashups, like Murder on the Polar Express and Silent Night Of The Lambs.

“Sondheim is a genius,” Landry said. “Almost every musical I do, I borrow from Sondheim — his triple rhymes and quadruple rhymes and how he broke the rules — just about everything I do has his influence.”

And Sondheim didn’t just light up Boston’s theater scene. In the case of the Colonial Theatre, he rallied to keep its lights on.

In 2015, it looked like it was going to be curtains for the historic space when Emerson College considered turning it into a student activity center.

In an interview with Boston Magazine, Sondheim said that would be a crime. “I’ve had shows which tried out in the Colonial, and it’s not only beautiful but acoustically first-rate, two qualities which are rare in tandem, even on Broadway," he said at the time. "For those of us involved in musical theater, it’s a treasure and to tear it down would be not only a loss, but something of a crime."

In the end, following a petition to save the theater and opposition on social media, Emerson reached a long-term agreement with Ambassador Theater Group to keep the theater and to return to its famed roots as a premier, pre-Broadway venue for drama.

While Sondheim will live on through his extensive body of work, Veloudos says it’s still hard to fathom that Sondheim has actually died. “Even though he hasn’t done much in the last 10 years, I'm going to miss his work. I’ll miss waiting for a new piece of brilliance to come from him,” Veloudos said.

Remembering the American master, Lockhart wrote, “One of the true joys of my career is that I get to meet, and know, amazing people. Incredibly talented musicians, dancers, actors, comedians. Incredibly intelligent and inspiring leaders. Sports legends. Everyone intersects with the Pops. However, the hour and a half that I spent with Sondheim in his Manhattan living room years ago, talking about our plans for a never-realized Sondheim 70th birthday celebration, ranks as the most memorable personal connection of my career. The word 'genius' is certainly overused, but I am convinced that Stephen Sondheim was the only true genius I have ever met.”