Ronnie James Dio or simply Dio, was an American heavy metal singer-songwriter and composer, and was also known for popularizing the sign of the horns in heavy metal. He fronted or founded numerous groups throughout his career, including Elf, Rainbow, Black Sabbath, Dio, and Heaven & Hell.

Dio is regarded as one of the greatest and most influential heavy metal artists of all time. Dio had a powerful, versatile vocal range and was capable of singing both hard rock and lighter ballads. He was awarded the “Metal Guru Award” by Classic Rock Magazine in 2006. He was also named the “Best Metal singer” at the Revolver Golden Gods Awards in 2010 and ranked as the genre’s best vocalist in 2013 by music journalist Sacha Jenkins.