Ronnie James Dio (born Ronald James Padavona, July 10, 1942 – May 16, 2010), was an American rock and heavy metal vocalist and songwriter. He performed with Elf, Rainbow, Black Sabbath, Heaven & Hell, and his own band Dio, among others. Other musical projects include the collective fundraiser Hear 'n Aid. He was widely hailed as one of the most powerful singers in heavy metal, renowned for his consistently powerful voice. He is credited with popularizing the "metal horns" hand gesture in metal culture.

Before his death, he was collaborating on a project with former Black Sabbath bandmates Tony Iommi, Geezer Butler, and Vinny Appice, under the moniker Heaven & Hell, whose only studio album, The Devil You Know, was released on April 28, 2009. He has sold over 47 million copies of albums with all of the bands he has worked with.