Mob Rules is Black Sabbath's tenth studio album, released in 1981 following the success of Heaven and Hell. It peaked at number 29 on the charts.
It was the first album to feature Vinny Appice on drums, who had replaced original member Bill Ward on the tour in support of the previous year's Heaven and Hell. This led to Ozzy Osbourne dubbing the line-up "Geezer and the three Wops".
It is rumoured that the cover art for this album, by famed artist Greg Hildebrandt, contains a heavily-disguised message that reads "KILL OZZY,". .