Hiatus And Seventh Star (1984–1986)

Following the completion of the Born Again tour in March 1984, vocalist Ian Gillan left Black Sabbath to re-join Deep Purple, which was reforming after a long hiatus. Bevan left at the same time, and Gillan remarked that he and Bevan were made to feel like "hired help" by Iommi. The band then recruited an unknown Los Angeles vocalist named David Donato. The new lineup wrote and rehearsed throughout 1984, and eventually recorded a demo with producer Bob Ezrin in October. Unhappy with the results, the band parted ways with Donato shortly after. Disillusioned with the band's revolving lineup, bassist Geezer Butler quit Black Sabbath in November 1984 to form a solo band. "When Ian Gillan took over that was the end of it for me", Butler later said. "I thought it was just a joke and I just totally left. When we got together with Gillan it was not supposed to be a Black Sabbath album. After we had done the album we gave it to Warner Bros. and they said they were going to put it out as a Black Sabbath album and we didn’t have a leg to stand on. I got really disillusioned with it and Gillan was really pissed off about it. That lasted one album and one tour and then that was it." Following Butler's exit, sole remaining original member Tony Iommi put Black Sabbath on hiatus, and began work on a solo album with keyboardist Geoff Nicholls. While working on new material, the original Black Sabbath lineup were offered a spot at Bob Geldof's Live Aid benefit concert; the band agreed, performing at the Philadelphia show, on 13 July 1985. The event marked the first time the original lineup appeared on stage since 1978, and also featured reunions of The Who and Led Zeppelin. Returning to his solo work, Iommi enlisted bassist Dave Spitz and drummer Eric Singer, and initially intended to use multiple singers, including Rob Halford of Judas Priest, ex-Deep Purple and Trapeze vocalist Glenn Hughes, and ex-Black Sabbath vocalist Ronnie James Dio. "We were going to use different vocalists on the album, guest vocalists, but it was so difficult getting it together and getting releases from their record companies. Glenn Hughes came along to sing on one track and we decided to use him on the whole album."

The band spent the remainder of the year in the studio, recording what would become Seventh Star. Warner Bros. refused to release the album as a Tony Iommi solo release, instead insisting on using the name Black Sabbath. Pressured by the band's manager, Don Arden, the two compromised and released the album as "Black Sabbath featuring Tony Iommi" in January 1986. "It opened up a whole can of worms really," Iommi explained, "because I think if we could have done it as a solo album, it would have been accepted a lot more." Seventh Star, which sounded little like a Black Sabbath album, incorporated more hard rock elements popularised by the 1980s Sunset Strip hard rock scene, and was panned by the critics of the era, although later reviewers such as AllMusic gave the album favourable reviews, calling the album "often misunderstood and underrated".

The new lineup rehearsed for six weeks, preparing for a full world tour, although the band were again forced to use the Black Sabbath name. "I was into the 'Tony Iommi project', but I wasn't into the Black Sabbath moniker," Hughes said. "The idea of being in Black Sabbath didn't appeal to me whatsoever. Glenn Hughes singing in Black Sabbath is like James Brown singing in Metallica. It wasn't gonna work". Just four days before the start of the tour, vocalist Glenn Hughes got into a bar fight with the band's production manager John Downing which splintered the singer's orbital bone. The injury interfered with Hughes' ability to sing, and the band brought in vocalist Ray Gillen to continue the tour with W.A.S.P. and Anthrax, although nearly half of the US dates would eventually be cancelled because of poor ticket sales.

One vocalist whose status is disputed, both inside and outside Black Sabbath, is Christian evangelist Jeff Fenholt. He has insisted that he was a singer in Black Sabbath between January and May 1985. Tony Iommi has never confirmed this, as he was working on a solo release that was later named as a Sabbath album. Fenholt gives a detailed account of his time with Iommi and Sabbath in Garry Sharpe-Young's book Sabbath Bloody Sabbath: The Battle for Black Sabbath.