Black Sabbath is a British music group that is considered one of the founders of heavy metal music. Founded by Ozzy Osbourne (vocals), Tony Iommi (guitar), Geezer Butler (bass) and Bill Ward (drums), they have experienced so many personnel changes that at one time only Iommi is left from the initial formation. Black Sabbath has also held several reunions with former members, both onstage and in the recording studio. Currently their status is a vacuum, with each member concentrating on his solo career.