Bob Weir (born Robert Hall Weir, October 16, 1947) is an American singer, songwriter, and guitarist, most recognized as a founding member of the Grateful Dead. After the Grateful Dead disbanded, Weir performed with The Other Ones, later known as The Dead, together with other former members of the Grateful Dead. Weir also founded and played in several other bands during and after his career with the Grateful Dead, including Kingfish, the Bob Weir Band, Bobby and the Midnites, RatDog, and his newest band Furthur.

Weir played mostly rhythm guitar during his career with the Grateful Dead. He is known for his unique style of complex voiceleading, bringing unusual depth and a new approach to the role of rhythm guitar expression.

Weir was born in San Francisco, California and raised by his adoptive parents in the suburb of Atherton. He began playing guitar at age thirteen after less successful experimentation with the piano and the trumpet. He had trouble in school because of undiagnosed dyslexia and he was expelled from nearly every school he attended, including Menlo School in Atherton. One of these was the Fountain Valley School in Colorado, where he befriended John Perry Barlow, who, along with Robert Hunter, would in time become the two main lyricists for the Grateful Dead.