An English rock band, formed in Birmingham in 1968, by guitarist Tony Iommi, bassist Geezer Butler, singer Ozzy Osbourne and drummer Bill Ward. The band has since experienced multiple line-up changes, with Tony Iommi the only constant presence in the band through the years. Originally formed as a heavy blues rock band named Earth, the band began incorporating occult themes with horror-inspired lyrics and tuned-down guitars. They also composed songs dealing with social instability, political corruption, the dangers of drug abuse and apocalyptic prophecies of the horrors of war.