The iconic band, the Grateful Dead, is mourning the loss of one of its original members.

Bob Weir, who co-founded the legendary psychedelic rock group in 1965 with fellow musicians Jerry Garcia, Phil Lesh, and Ron McKernan, has passed away at the age of 78, as announced by his family on January 10.

“With a heavy heart, we announce the passing of Bobby Weir,” the family shared via his Instagram account. “He left us peacefully, surrounded by loved ones, after bravely overcoming cancer in his own unique way. Sadly, he was unable to overcome underlying lung complications.”

Despite his health struggles, the beloved guitarist didn’t let his ailments keep him from performing. He took to the stage with Dead and Company in San Francisco, his hometown, just a few weeks after starting cancer treatment.

“Bobby’s last months were a testament to the spirit that fueled his life,” the family’s statement added. “His performances were emotional, soulful, and radiant—not farewells, but rather a series of heartfelt gifts. A final act of perseverance.”