Bob Weir, guitarist, singer and founding force of the Grateful Dead, has died at the age of 78, his family announced Saturday. A statement shared on Weir’s Instagram said he passed away peacefully, surrounded by loved ones, after surviving cancer but later facing complications related to lung illness.

Weir joined the band, then known as the Warlocks, in San Francisco in 1965 when he was just 17. Alongside Jerry Garcia, he helped shape the band’s signature sound through decades of relentless touring and improvisational live shows that defined the 1960s counterculture and beyond.

He wrote or co-wrote enduring songs such as Sugar Magnolia, One More Saturday Night and Mexicali Blues. After Garcia’s death in 1995, Weir became the band’s most visible torchbearer, continuing its legacy through projects like Dead & Company.

Weir is remembered as a tireless performer whose music united generations of devoted fans.