Ian Gillan

He joined the group in 1969, and just completed a huge tour late last year.

These rock and metal singers left the bands they were in and then came back years later for another round (or multiple).

To enhance or to play straight up?

See what was going on in music 50 years ago.

There was reason for excitement, given the band's resurrection behind Ozzy Osbourne's first replacement, Ronnie James Dio.

Write off their obscure and latter-day records at your own peril.

He actually submitted a resignation letter to the band while still on tour promoting 1973's 'Who Do We Think We Are.'