Who replaced Ozzy Osbourne as lead vocalist in 1979?

Ronnie James Dio replaced Ozzy Osbourne as Black Sabbath’s lead vocalist in 1979.

Dio joined the band after Osbourne was fired in April 1979 amid serious problems involving alcohol, drugs, and his declining ability to work with the group. Dio had recently left Rainbow, where he had established himself as a powerful and distinctive rock singer. He met guitarist Tony Iommi in Los Angeles later that year, and the two quickly began discussing a new musical project.

Dio’s first Black Sabbath album was Heaven and Hell, released in 1980. His arrival produced a significant change in the band’s sound: his clear, dramatic high-register voice contrasted sharply with Osbourne’s more conversational and eerie delivery. The new lineup also wrote “Children of the Sea,” one of the album’s best-known songs.

Dio was not simply a temporary stand-in. He became one of Black Sabbath’s most important vocalists, returning in the early 1990s for Dehumanizer. His first tenure also produced Mob Rules in 1981, although he left the band in 1982 after tensions surrounding the Live Evil project.