Grateful Dead co-founder and guitarist Bob Weir has died at age 78. His family announced his peaceful passing, stating he succumbed to underlying lung issues after courageously beating cancer. Weir, a founding member since 1965, was known for his rhythm guitar, songwriting, and vocals on classics like "Sugar Magnolia" and "Truckin'." His death leaves Bill Kreutzmann as the sole surviving original member of the iconic band, with tributes pouring in from across the music world.