Black Sabbath were an English rock band, formed in Aston, Birmingham in 1969 by Ozzy Osbourne (lead vocals), Tony Iommi (guitar), Geezer Butler (bass guitar) and Bill Ward (drums). The band has since experienced multiple line-up changes, with Tony Iommi the only constant presence in the band through the years. A total of twenty-two musicians have at one time been members of Black Sabbath. Originally formed as a heavy blues rock band named Earth, the band began incorporating occult- and horror-inspired lyrics with tuned-down guitars, changing their name to Black Sabbath and achieving multiple platinum records in the 1970s. Despite an association with occult and horror themes, Black Sabbath also composed songs dealing with social instability, political corruption, the dangers of drug abuse and the often apocalyptic prophesies of the horrors of war.
Black Sabbath are cited, along with Led Zeppelin as pioneers of heavy metal. The band helped define the genre with releases such as quadruple-platinum Paranoid, released in 1970. They were ranked by MTV as the "Greatest Metal Band" of all time, and placed second in VH1's "100 Greatest Artists of Hard Rock" list, behind Led Zeppelin.[5] Rolling Stone has posited the band as 'the heavy-metal kings of the '70s'. They have sold over 15 million records in the United States alone[7] and more than 100 million records worldwide.
Vocalist Ozzy Osbourne's heavy alcohol and cocaine usage led to his being fired from the band in April 1979, after which he began a very successful solo career, selling more than 100 million albums. He was replaced by former Rainbow vocalist Ronnie James Dio. After a few albums with Dio's vocals and songwriting collaborations, Black Sabbath endured a revolving line-up in the 1980s and 1990s that included vocalists Ian Gillan, Glenn Hughes, Ray Gillen and Tony Martin. In 1992, Iommi and Butler rejoined Dio and drummer Vinny Appice to record Dehumanizer. The original line-up reunited with Osbourne in 1997 and released a live album, Reunion. The 1979–1982 and 1991–1992 line-up featuring Iommi, Butler, Dio and Appice reformed in 2006 under the moniker Heaven & Hell until Dio's death on 16 May 2010. Wikipedia

Black Sabbath to Reunite For New Album and Tour

After years of rumors, Tony Iommi has announced that the original lineup of Black Sabbath is going to reunite for a new album and tour. "We’re really looking forward to it and I think the stuff we’ve been writing is really good,’’ the guitarist told the Birmingham Mail. "It’s all been very hush-hush. Ozzy’s been the worst at trying to hold it back. He’s doing a lot of TV and he’s being asked stuff about a reunion and he’s going 'Well, I never say never.'"

Just six months ago, Sabbath bassist Geezer Butler put out a press release saying a reunion would never happen. "I would like to make it clear, because of mounting speculation and rumours, that there will be definitely no reunion of all four original members of Black Sabbath," he wrote. "Whether to record an album or to tour." Rollingstone.com