Weir had been diagnosed with cancer in July and beat it, but “succumbed to underlying lung issues,” according to a statement on his website.

Bob Weir, a founding member of the Grateful Dead whose rhythm guitar work, songwriting and tireless touring helped push traditional American blues and folk music into the modern era, has died, according to a statement posted Saturday to his official website.

He was 78.

The statement, also posted to social media, said Weir had been diagnosed with cancer in July and beat it but “succumbed to underlying lung issues.”

“He transitioned peacefully, surrounded by loved ones, after courageously beating cancer as only Bobby could,” the statement said.

Across more than six decades, Weir was one of music’s true road warriors, performing thousands of shows with almost a dozen bands. And though he often stood figuratively (and sometimes literally) in Jerry Garcia’s shadow, Weir eventually assumed the status of elder statesman of the “jam band” music genre that spun off from the Dead.

Born in San Francisco in 1947, Weir gravitated to folk music in his teenage years. At the age of 16, it was a chance encounter with Garcia in a Palo Alto, California, music store on New Year’s Eve 1963 that would start one of the most important friendships in rock history. Together, Garcia and Weir formed the basis for the Dead’s emergence as not just a band but a counterculture unto itself.

Emerging from the psychedelic scene in the Haight-Ashbury neighborhood of San Francisco, Weir’s early days of the Dead are well chronicled as part of the rise of the hippie movement, most notably Ken Kesey’s “Acid Tests,” LSD-fueled parties at which the Dead performed. Though middling in record sales, the Dead’s aggressive touring regimen — combined with a policy that allowed fans to record shows and trade their favorite recordings — built a following that would grow organically over the decades.

In the coming years, Garcia and Weir, initially a boyish figure next to his older and usually hairier bandmates, would become the faces of the Dead and its increasingly large cultural footprint. The two shared vocal duties while Weir’s rhythm guitar laid the foundation for Garcia’s now legendary improvisational playing. Weir penned some of the Dead’s most enduring songs, including “Jack Straw,” “Sugar Magnolia” and “Playing in the Band.”

The band swerved across the music industry’s established lanes of short pop songs and thematic, marketing-friendly albums to create live, long-form journeys that matched the demands of psychedelia.

“We didn’t make great records,” Weir said in an interview with journalist Dan Rather. “We were real good at playing live. And that’s what people wanted.”

Weir’s bond with Garcia formed the core of the Dead, with Weir speaking of Garcia as a big brother.

“They say that blood is thicker than water, and what we had was way thicker than blood,” Weir said of Garcia and the Dead in the interview with Rather.

The Dead’s enduring popularity through the 1980s and early 1990s, thanks in large part to near-constant touring, kept Weir center stage. With cutoff jeans and tank tops, Weir became the closest thing the counterculture band had to a “heartthrob,” as The New Yorker once put it in a profile of the band.

But Garcia’s health problems began to hamper the band. On Aug. 9, 1995, Weir stepped up to microphones to confirm reports that Garcia had passed away.

For another three decades after Garcia’s death, Weir played in various bands, some with other members of the Dead, some without. By the mid-1990s, a new crop of bands including Phish, Widespread Panic, Blues Traveler and many others had built on the Dead’s foundation to deliver various combinations of rock, blues, jazz, bluegrass and folk to live audiences. The jam band movement had taken shape, and Weir would remain firmly a part of it.

That only sustained the popularity of the Dead’s music. In August 2025, Weir’s most recent project, Dead & Company, which included longtime Grateful Dead drummer Mickey Hart and guitarist John Mayer, drew roughly 180,000 people over three shows at San Francisco’s Golden Gate Park.

“Bob’s return to Golden Gate Park this past summer brought out the best of our city — music, community, and joy,” San Francisco Mayor Daniel Lurie said Saturday in a statement on Weir’s passing.

Weir received a bevy of honors: Kennedy Center honors and induction to the Rock & Roll Hall of Fame as a member of the Dead, the first ever Les Paul Spirit Award winner and a lifetime achievement award from the Americana Honors & Awards.

Dead concert recordings have also maintained a cult following online, where nearly 18,000 digital files with concerts since 1965 are part of the Internet Archive.

And while the Dead were not usually much for politics, Weir increasingly embraced liberal and progressive politics starting in the early 2000s and continuing through later years when he endorsed Kamala Harris and Tim Walz. Weir also dedicated time to philanthropic efforts, winning the MusiCare’s Persons of the Year award in 2025 along with Hart.

California Gov. Gavin Newsom and his partner, Jennifer Siebel Newsom, released a joint statement Saturday night calling Weir “a true son of California” who “helped create the soundtrack of a generation.”

“What set him apart was not just his music — it was his deep love for the people who heard it, his ability to connect with audiences as he shared stories that brought joy,” the couple said. “Weir was — and will always be — a king of psychedelic rock.”

At the other end of the nation, the Empire State Building was lit up in tie-dye colors to memorialize Weir and the music that that made the counterculture’s trademark swirling pigmentation seem to dance.

Seán Ono Lennon, son of Yoko Ono and John Lennon, reacted to Weir’s death with a brief statement and a photo posted to X: “He will be missed. Bob Weir R.I.P.”

A post on Bob Dylan’s X account on Saturday night featured a black-and-white photo of Weir, Garcia and himself performing on stage during the Bob Dylan and the Grateful Dead 1987 Tour. No words were included in the post.

The Al Hirschfeld Foundation, a nonprofit that supports cultural institutions in part by using income from exhibits of the late artist’s iconic cartoon sketches, posted a photo of an Al Hirschfeld rendition of the Grateful Dead from 1995 as a way to memorialize Weir.

The statement announcing Weir’s death said surviving loved ones Natascha, Monet and Chloe are thankful for the outpouring of love, and asked that their privacy be respected.

Weir is also survived by a handful of Grateful Dead bandmates, including drummers Hart and Bill Kreutzmann.

“There is no final curtain here, not really,” the statement said. “Only the sense of someone setting off again. He often spoke of a three-hundred-year legacy, determined to ensure the songbook would endure long after him. May that dream live on through future generations of Dead Heads.”