Ronnie James Dio: Singer who worked with Ritchie Blackmore in Rainbow and replaced Ozzie Osbourne in Black Sabbath

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As lead vocalist with some of the biggest heavy metal bands of the 1970s and '80s, and fronting his own group, Ronnie James Dio bestrode festival stages and delighted millions of rock fans around the world. He also popularised the "devil's horns" gesture beloved of metal fans of all ages, and made it his trademark. "The 'sign'" is a superstitious symbol used by many older cultures," he remarked of the gesture he picked up from his Italian grandmother. "It's meant to intercept the evil eye and other curses, and what better place to use it than at a metal show?"

The American-born singer first came to prominence in 1975 with Ritchie Blackmore's Rainbow, the band formed by the guitarist just before he left Deep Purple. Dio co-wrote the memorable "Man On The Silver Mountain", the mighty "Kill The King" and the anthemic "Long Live Rock'n'Roll", as well as much of the material featured on the first four Rainbow albums, but he was edged out in 1979. At the behest of Sharon Arden, the daughter of band manager Don Arden, he joined Black Sabbath, replacing their original frontman Ozzy Osbourne, who had become increasingly unreliable, and revitalised the inventors of the heavy metal genre with his notable contributions to the million-selling albums Heaven And Hell and Mob Rules.

"It was a challenge to resurrect a band that was just one of my favorites," he later reflected. "To be able to give them the pride back that they deserved was something that I shall never forget. I was very happy to do that for them. And we made great music."

However, he stormed out at the end of 1982 and launched his own group, Dio, with whom he issued 10 studio albums including the majestic Holy Diver, The Last In Line, Sacred Heart and Dream Evil. Having briefly rejoined Sabbath for the Dehumanizer album in 1992, he again toured with its mainstays, the bassist Geezer Butler and the guitarist Tony Iommi, as Heaven & Hell, and recorded The Devil You Know album with them in 2008.

Dio wasn't as impulsive or as mercenary as the above résumé, worthy of one of rock archivist Pete Frame's legendary Rock Family Trees, might imply. "Because I've been in and out of bands, people think I'm difficult," he said in 1997. "That comes about because I'm very intense about what I do. I have a really high standard, and I expect people around me to reach that standard as well. That's probably unfair."

The vocalist also admitted he occasionally took his obsession with "sword and sorcery" and fantasy imagery too far, but strongly argued for his right to do so. "Who wants to talk about love and relationships when you have these dark vehicles to use? Dark themes are generally about things we can never see, so you must use your imagination. After all, who has ever seen a dragon? The dragon represents bad government, brutal rulers, and technology."

Indeed, despite his Mephistophelian appearance on stage, Dio was one of rock's nicest guys, happy to chat at functions such as the Classic Rock Awards and always willing to sign autographs for fans, including many who went on to form their own bands, like the Metallica drummer Lars Ulrich.

Born Ronald James Padavona, in Portsmouth, New Hampshire, in 1942, he was an only child, and grew up in Cortland, upstate New York; he retained a fierce loyalty to the New York Yankees baseball team throughout his adult life. He played the French horn and the trumpet before picking up the bass after joining The Vegas Kings. He made his recording debut with Ronnie & The Redcaps in 1958 and soon became their sole vocalist. Three years later, he took up the stage name Dio after the New York mobster Giovanni Dioguardi, aka "Johnny Dio". As Ronnie Dio & The Prophets, the band issued several singles on various labels, evolving into The Electric Elves in 1967 and then Elf two years later.

The Deep Purple bassist Roger Glover produced their first three albums and asked Dio, who had turned down a scholarship at the Juilliard School of Music, to sing lead on several songs for another of his productions, the concept album The Butterfly Ball and The Grasshopper's Feast, including the 1974 European hit single "Love Is All". Elf also supported Purple, and Blackmore and Dio struck up a songwriting partnership.

Named after The Rainbow Bar And Grill, Blackmore's favourite haunt, the band that recorded Ritchie Blackmore's Rainbow, their debut, comprised most of Elf but by their second album, Rainbow Rising, the guitarist had started to ring the changes and brought in seasoned musicians of the calibre of drummer Cozy Powell. With Blackmore's incendiary playing and Dio's formidable semi-operatic voice, Rainbow established a strong reputation as a concert attraction.

"That band was created by the two of us with a special purpose in mind," Dio explained. "We both loved the same kind of music, which was classical music. We were both real Bach aficionados. That was our point of reference. Rock 'n' roll music was what we loved. Deep Purple was my favorite band on earth, Ritchie was my hero." However, he continued, "Rainbow went astray after a while. It became a pop band, and that's not the way we started, nor the way it was supposed to be."

The singer performed just as well at the helm of Black Sabbath and won over the group's long-standing fans, although Ian Gillan's subsequent tenure with Sabbath was the chapter in the group's tumultuous history that inspired the film This Is Spinal Tap. Dio was no egotist but saw the logic in using his stage name for his next band. When I caught Dio in the mid-1980s, he walked out of a drawbridge at the centre of a huge mock-up of a castle that dominated the stage at the Edinburgh Playhouse, a mirth-inducing moment. Within minutes, he was belting out the Who-like "Hungry For Heaven" single, and had won me back.

Given his connections and his international standing, the singer was ideally placed when he and his then Dio bandmates, the bassist Jimmy Bain and the guitarist Vivian Campbell, decided to emulate the charity projects Band Aid and USA For Africa and came up with the Hear'N Aid "supergroup" concept in 1985. The triumvirate co-wrote "We're Stars", recorded it with members of Blue Öyster Cult, Judas Priest, Mötley Crüe and many other rock groups, and raised $1 million for famine relief in Africa.

"I consider myself a singer, not a shouter," he said in 2007. "It's always interesting when fans come up to me and say, 'Man, nobody screams like you!' I know they mean it as a compliment, but inside I'm going, 'I'm not a screamer, I'm a singer.' It's about a marriage of technique and feel, emotional content – not just screaming,"

Dio's music and lyrics had cross-generational appeal: he was lampooned in South Park and had a cameo in the 2006 Tenacious D movie The Pick of Destiny. "Most people have careers that last from three to five years, especially in metal," he admitted. "When you've had this good a run, you certainly don't complain."

Paying tribute to his former Rainbow bandmate, who died of stomach cancer, Blackmore said: "Ronnie had a unique and wonderful voice. He will be sadly missed in the rock'n'roll world."

Ronald James Padavona (Ronnie James Dio), singer and songwriter: born Portsmouth, New Hampshire 10 July 1942; married firstly Loretta Berardi (marriage dissolved; one adopted son), secondly Wendy Galaxiola; died Los Angeles 16 May 2010.