Grateful Dead co-founder/bassist Phil Lesh has died at the age of 84, according to a social media statement that did not provide a cause.

The musician "passed peacefully this morning (10/25)," per the statement. "He was surrounded by his family and full of love. Phil brought immense joy to everyone around him and leaves behind a legacy of music and love. We request that you respect the Lesh family’s privacy at this time.”

A Berkeley, California, native, Lesh became interested in the Bay Area's experimental music scene in the late 1950s, during which he once collaborated with then-fledgling composer Steve Reich and eventually met Jerry Garcia at a party. The pair reunited five years later, when Garcia asked Lesh to join the proto-Grateful Dead band The Warlocks on bass even though Lesh didn't know how to play the instrument.

Within six months, that group became known as the Grateful Dead and played its first show under that name in December 1965. Lesh was on stage for every jam-heavy Dead concert that followed until Garcia's 1995 death, and joined his former bandmates to keep the legacy alive in various later iterations, including The Other Ones and Furthur.

The musician co-wrote such favorites as "St. Stephen," "Cumberland Blues" and "Truckin'," and also sang lead on "Box of Rain" and "Unbroken Chain."

Lesh, who required a liver transplant in 1998 due to hepatitis C, also survived a 2006 bout with prostate cancer. He last performed as part of the Grateful Dead with Bob Weir, Mickey Hart and Bill Kreutzmann at a series of 2015 concerts in celebration of the band's 50th anniversary, the same year he was diagnosed with bladder cancer, but he continued to tour and play regularly with his band Phil Lesh and Friends.

Earlier this week, the Recording Academy announced that the Dead would be honored as MusiCares Persons of the Year for 2025 in recognition of its members' long-standing advocacy efforts, including Lesh's work with the Unbroken Chain Foundation. Tonight from 9-10 PM ET, the Empire State Building will shine in tie-dye in his memory.