James Robert "Bob" Mosley (born December 4, 1942) is an American musician principally known as the bass player and one of the songwriters and vocalists for the band Moby Grape.

Mosley spent his adolescence in San Diego, where he graduated from Kearny High School.

He also played and sang with Jerry Miller and Don Stevenson in The Frantics, "Someday" (not the Moby Grape song) and "Human Monkey" on Action Records (AF1113) in 1966.

Mosley's career has been plagued by the challenges of schizophrenia, as was the case with Moby Grape bandmate Skip Spence.

Earlier attempts by Moby Grape band members to help Mosley out of homelessness had been less successful.

One such attempt is described by Peter Lewis as follows: "We went to find Bob, and there he was, living in this cardboard box.