Image copyright Getty Images Image caption Sondheim enjoyed a prolific career composing thousands of songs for stage, screen and television
He’s the man who wrote such acclaimed musicals as Company, Sunday in the Park with George and West Side Story.
But it was Stephen Sondheim’s comments on Donald Trump that got him in trouble.
His 2005 poem – which he wrote while, he claimed, he was “on the road” – attacked the US president.
He died of complications of lung disease, aged 91.
In his book, A Sondheim Companion, his biographer Scott Sanders described the playwright as “a nearly religious man” whose words “impeach those in power”.
Born Stephen Paul Mandell on 28 October 1925, the New York-born Sondheim, who went to Cambridge University, studied music at the University of Michigan.
Afterwards, he worked as a music composer for various companies and acts, including The Lionel Hampton Band, before writing more than 15 one-act plays.
His first full musical production, Sunday in the Park with George, won five Tonys in 1967.
Image copyright WBR Image caption Sondheim’s neo-noir play Sunday in the Park with George won five Tonys in 1967
It followed the lives of an unhappy husband and wife in contemporary America.
His best-known works include Follies, Into the Woods, Sunday in the Park, Company and Sondheim on Sondheim.
Tributes have poured in, with actor Bradley Cooper praising Sondheim as a “genius” whose creativity revolutionised the musical theatre.
Cooper, who starred in West Side Story and Into the Woods, also described Sondheim as an “absolute brilliant, inspirational genius” on Twitter.
“My condolences to his family and friends,” he wrote.
Image copyright Sky Images Image caption The New York Times quotes George Manahan, the editor of the Herald Tribune as saying Sondheim “was the best American writer of musicals that we’ve had”.
“I think for me he was, probably, of the 20th century the most powerful writer of American musicals. He revolutionised the medium in such a way that you could read every musical comedy that came out after that.”
David Picozzi, the former drama critic for the New York Times, added: “Sondheim wrote musicals that defined our culture and art with joy. He was not taken seriously until the vitriol for his book, revealing Trump, changed it. He was accused of ‘telling f-bomb jokes’, and worse. That’s a hit against someone who still takes the pains to play proper piano.”