Dio was an American heavy metal band formed in 1982 and led by vocalist Ronnie James Dio.

Dio left Black Sabbath with intentions to form a new band with fellow former Black Sabbath drummer Vinny Appice. The name Dio was chosen because it made sense from a commercial standpoint, as the name was already well known at that time.

The band released ten studio albums and had numerous lineup changes over the years, with Dio himself being the only constant member. Guitarists included Vivian Campbell, Craig Goldy, Doug Aldrich, Warren DeMartini, Tracy G, Jake E. Lee and Rowan Robertson.

The band dissolved in 2010 when Ronnie James Dio died of stomach cancer at the age of 67. R. J. Dio has sold over 50 million records worldwide.