David Walker is an English singer and guitarist who has been front-man for a number of bands; most notably The Idle Race, Savoy Brown and Humble Pie, he also served briefly with Fleetwood Mac and Black Sabbath.

Black Sabbath were an English rock band formed in Birmingham in 1968 by guitarist Tony Iommi, drummer Bill Ward, bassist Geezer Butler and vocalist Ozzy Osbourne. They are often cited as pioneers of heavy metal music. The band helped define the genre with their first three albums Black Sabbath, Paranoid and Master of Reality (1971). Following Osbourne's departure in 1979, the band underwent multiple line-up changes, with Iommi being the only constant member throughout their history.