LOS ANGELES — Peter Yarrow, the singer-songwriter best known as one-third of Peter, Paul and Mary, the folk-music trio whose impassioned harmonies transfixed millions as they lifted their voices in favor of civil rights and against war, died Tuesday. He was 86.

Yarrow, who also co-wrote the group’s most enduring song, “Puff the Magic Dragon,” died in New York, publicist Ken Sunshine said. Yarrow had bladder cancer for the past four years.

During an incredible run of success spanning the 1960s, Yarrow, Noel Paul Stookey and Mary Travers released six Billboard Top 10 singles, two No. 1 albums and won five Grammys.

They also brought early exposure to Bob Dylan by turning two of his songs, “Don’t Think Twice, It’s All Right” and “Blowin’ in the Wind,” into Billboard Top 10 hits as they helped lead an American renaissance in folk music.

After an eight-year hiatus to pursue solo careers, the trio reunited in 1978 for a “Survival Sunday,” an anti-nuclear-power concert that Yarrow had organized in Los Angeles. They would remain together until Travers’ death in 2009. Upon her passing, Yarrow and Stookey performed separately and together.

Born May 31, 1938, in New York, Yarrow was raised in an upper middle-class family that he said placed high value on art and scholarship. He took violin lessons as a child, later switching to guitar as he came to embrace the work of such folk-music icons as Woody Guthrie and Pete Seeger. He graduated with a degree in psychology from Cornell University in 1959.

He returned to New York City where he worked as a struggling Greenwich Village musician before meeting impresario Albert Grossman, who was looking to put together a group that would rival the Kingston Trio.

But Grossman wanted a trio with a female singer and a member who could be funny enough to keep an audience engaged with comic patter. Yarrow suggested Stookey, a guitar-strumming Greenwich Village comic, who knew Travers.

Their first album, 1962’s “Peter, Paul and Mary,” reached No. 1 on the Billboard chart. Their second, “In the Wind,” reached No. 4 and their third, “Moving,” put them back at No. 1.

From the earliest albums, the trio sang out against war and injustice. They could also show a soft and poignant side, particularly on “Puff the Magic Dragon,” which Yarrow had written during his Cornell years with college friend Leonard Lipton.

It tells the tale of Jackie Paper, a young boy who embarks on countless adventures with his make-believe dragon friend until he outgrows such childhood fantasies and leaves a sobbing, heartbroken Puff behind. Some insisted they heard drug references in the song; Yarrow said it reflected the loss of childhood innocence and nothing more.

After recording their last No. 1 hit, a 1969 cover of John Denver’s “Leaving on a Jet Plane,” the trio split up the following year to pursue solo careers.

That same year Yarrow had pleaded guilty to taking indecent liberties with a 14-year-old girl who had come to his hotel room with her older sister to ask for autographs. The pair found him naked when he answered the door and let them in. Yarrow, who resumed his career after serving three months in jail, was pardoned by President Jimmy Carter in 1981. Over the decades, he apologized repeatedly.

Yarrow, who with Travers and Stookey had supported Democratic Sen. Eugene McCarthy’s 1968 presidential bid, met the Minnesota senator’s niece, Mary Beth McCarthy, at a campaign event. The couple married the following year. They had two children before divorcing, but they remarried in 2022. In addition to his wife, he is survived by a son, Christopher; a daughter, Bethany; and a granddaughter, Valentina.