Who played bass in Metallica's lineup when The Black Album was released in 1991?

Jason Newsted was Metallica's bassist when The Black Album was released in 1991.

Newsted joined Metallica in 1986 after the death of Cliff Burton, becoming the band's third bassist. He had previously played in the Arizona thrash-metal band Flotsam and Jetsam. By the time of the Black Album, he had been part of Metallica for several years and was an established member of the touring lineup.

The album's bass credit has a notable complication. Producer Bob Rock performed the bass parts on the studio recording, while Newsted was the band's official bassist and played the material live. This distinction is why references to the album may mention both Newsted and Rock in connection with bass.

Newsted later left Metallica in 2001. Robert Trujillo joined the band in 2003, so he was not part of the Black Album-era lineup. Cliff Burton, meanwhile, had died before the album's recording and did not play on it.