Bob Weir, the guitarist who co-founded the Grateful Dead, has died aged 78.

Weir, a cornerstone of the California psychedelic rock group and many of its offshoots, passed away after a battle with cancer and lung issues, according to a post on his Instagram.

"There is no final curtain here, not really. Only the sense of someone setting off again," the post says, noting his hopes that his legacy and lengthy catalogue will live on.

The post says he "transitioned peacefully, surrounded by loved ones".

"He often spoke of a three-hundred-year legacy, determined to ensure the songbook would endure long after him," the post continues. "May that dream live on through future generations of Dead Heads."

With a career spanning more than 60 years, Weir's big break was in 1965 with the founding of the Grateful Dead. Within a few years, they became a force within San Francisco's characteristic counterculture.

Quickly their style began shaping rock music - blending psychedelia and 1960s drug culture with musical tones that fused folk and Americana. They are considered one of the pioneers of jam bands.

The group was inducted in the Rock and Roll Hall of Fame in 1994 and received a Lifetime Achievement Award by the Grammy's in 2007.

The group officially halted in 1995 with the death of fellow co-founder Jerry Garcia.

But Weir was involved in various spin-offs, including Dead & Company, which had a residency at the Las Vegas Sphere in 2024 and 2025.

Weir was diagnosed with cancer in July and even while being treated, he continued to perform, according to the post on his page.

"Those performances, emotional, soulful, and full of light, were not farewells, but gifts," the post says. "Another act of resilience. An artist choosing, even then, to keep going by his own design."

He beat cancer before his death, the posts adds. It's unclear what type of cancer he had been diagnosed with.

His family, including wife Natascha and children Shala and Chloe, asked for privacy but said they appreciated the "outpouring of love, support, and remembrance".

Tributes started to pour in late on Saturday from fellow musicians. Even the Empire State Building in New York City honoured the rock legend by shining with tie-dye colours to memorise him.

Slash, guitarist of Guns N' Roses, posted a photo of Weir playing on stage. He wrote "RIP" with a broken-heart emoji.

Former Eagles guitarist Don Felder posted a lengthy tribute.

"I first saw Bob at Woodstock with the Grateful Dead and was blown away by that whole band, and the musicianship," Felder posted on Instagram with a photo of himself with Weir.

"I feel so blessed to have been able to have him sing on 'Rock You' from American Rock and Roll. Until we meet again, amigo."

His former publicist, Dennis McNally, spoke with BBC News about his music and the fun memories they shared.

"He had a very off-kilter, unusual sense of humour that was dry and funny," he said. "The road was his life, and music was his life."

He said playing and serving the music was what "he was put on Earth for and he did it to the end".