Bob Weir co-founded the Grateful Dead in 1965 with Ron McKernan, Phil Lesh and Bill Kreutzmann. The band has sold over 35 million records worldwide in various lineups. The band split up in 1995 following the death of frontman Jerry Garcia, but reunited in 2015 for the "Fare Thee Well" tour.
"Bobby will forever be a guiding force whose unique artistry transformed American music," the family wrote in a statement on Instagram.
Weir has played in several lineups since the 2015 tour, including Dead & Company with Mickey Hart and Bill Kreutzmann. Dead & Company played Grateful Dead songs with singer John Mayer as the frontman.
Bob Weir turned 78.
