The name is Italian for God. Which is just as well because Ronnie James (born Ronald James Padavona, 10 July 1942) is metal's best candidate for one.
If fronting two legendary bands (Rainbow and Black Sabbath) wasn't enough, Dio then formed his own eponymous band, unleashing an indisputable classic with 1980's Holy Diver. He also brought the iconic devil horn hand signal to metal along the way.
After nearly 50 years in the business, you'd think the 67-year-old would be cutting back. That's not what Dio does.
In 2007 he reunited with his former Sabbath bandmates in Heaven & Hell and taught the young pups how it's done with this year's Devil You Know album.
D is also for Doom Metal - slow, sludgy, riff-laden and heavier than a Kuwaiti tanker, this subgenre owes everything to pioneers Sabbath and their peers from the US, Pentagram.