Every rock concert-going teenager for two generations knows the familiar "evil eye" or "devil's horns" hand signal. It is often displayed by concert-goers when they want to leave others with the impression that the music or overall feeling at the concert is going very well. While the sign has ancient roots in Turkey and Greece, an Italian-American is responsible for popularizing it in the United States, beginning in the 1970s.

Ronnie James Dio was born Ronald James Padavona. He was born an only child of parents from Portsmouth, New Hampshire. When he was a toddler, the family relocated to Cortland, New York. As staunch Italian Roman Catholics, Dio's parents raised him in their faith, taking him to church and enrolling him in Catechism classes. Their son was not happy with what the church offered him, and his growing frustration with Christianity led to an eventual rejection and foreshadowed certain aspects of his music career.

Dio first developed an interest in music as a teenager. In school he played trumpet and French horn. Before he was out of his teens he was playing with local bands, eventually joining The Vegas Kings, for whom he played bass guitar. His singing skills were polished as well, and he was soon the lead singer of the band. After high school, he continued to pursue a music career, but first he enrolled at the University of Buffalo. He declared a major in pharmacy but only stayed for one year. He returned to music instead. He tried academics again, applying to and receiving a scholarship to study music at Julliard, but turned down the offer when he learned he would not be able to concentrate in rock music.

The bands he subsequently formed went through various incarnations and name changes, but one name stuck; and that was the name he chose for himself. He bestowed the moniker "Dio" upon himself in honor of a mafia member named Johnny Dio. In 1979, Ozzy Osbourne left the band Black Sabbath, and Dio was invited to replace him. The infusion of Dio's energy, powerful vocals and bass guitar revitalized the band and their albums Heaven and Hell, Mob Rules, and Live Evil sold millions of copies and earned the band great acclaim in the rock community. In 1982, Dio left the band due to ongoing disagreements, though he did return briefly ten years later to record Dehumanizer.

Dio was inducted into the Rock Walk of Fame on Hollywood's Sunset Boulevard in 2007. He was married twice. He and his first wife, Loretta Berardi, adopted a son. Later, the couple divorced and Dio married Wendy Galaxiola. She was also his manager and currently chairs the organization, Children of the Night, which works to save children from prostitution. In late 2009, Wendy publicly announced that her husband had received a diagnosis of stomach cancer. He underwent seven series of chemotherapy, and for a time it appeared he would beat cancer. However, he succumbed to the disease in May 2010. Wendy posted the following on Dio's official website: "Today my heart is broken, Ronnie passed away...[he] knew how much he was loved by all. We so appreciate the love and support that you have all given us...Please know he loved you all and his music will live on forever."

A memorial service was held for Dio in Los Angeles. The service was public and many fans and friends attended and many had to sit outside and watch the service on television screens. The notorious Westboro Baptist Church held a small rally, denouncing Dio as a Satanist. Wendy responded to the protest by saying that "Ronnie hates prejudice and violence. We need to turn the other cheek on these people that only know how to hate someone they didn't know. We only know how to love someone we know!"