Ronnie James Dio (RIP) in Black Sabbath was amazing. No-one could really imagine how it would sound and in many ways the line-up was written off before they started. That all changed once the album came out and it is safe to say that Heaven and Hell is one of the all time classic rock albums.
Dio just has a magic about him, he epitomized the whole Heavy Metal life style, I really regret never seeing him live. He had an amazing way of making an album his own without changing what the band sounded like, he just kind of made it Dio without killing the spirit of the band. If he’s not singing you can hear its Sabbath and when in Rainbow same thing. Dio was the pinnacle of what a frontman for a Heavy Metal band should be.