Rock 'n' roll never dies, but as any fan can tell you, band lineups are a lot less permanent — and for groups that have been together for decades, the personnel shifts can be hard to keep track of. With that in mind, we’ve decided to take a band-by-band look at the ins and outs of some of our favorite acts’ rosters, pausing to sample the music along the way.

For this installment, we're taking a look at the metal pioneers Black Sabbath – and as you'll see they've had a lot of lineup changes over the last four decades and change; in fact, guitarist Tony Iommi is the only band member who appears on every Sabbath record (so far).

Things started off simply enough. Apart from a brief spat with singer Ozzy Osbourne, the original foursome (which also includes Iommi, bassist Geezer Butler and drummer Bill Ward) stayed together for a decade, crafting six undisputed classic albums and two other damn good ones. When Ozzy ultimately did leave, former Rainbow singer Ronnie James Dio proved to be exactly the breath of fresh air the group needed. But then Ward left, and then Dio left, and then ... well, it gets pretty complicated pretty quickly.

With Black Sabbath currently on their farewell tour as of this February 2016 posting, we'd like to be able to tell you that everything came full circle, with the original lineup happily sharing one last series of curtain calls with their fans around the world. Unfortunately, a nasty split with Ward has kept that from happening ... so far.