On 13 March 2006, in the ballroom of the Waldorf-Astoria in New York, the Rock and Roll Hall of Fame inducted Black Sabbath, and the two men who walked up to make the speech were James Hetfield and Lars Ulrich of Metallica, whose band then played "Hole in the Sky" and "Iron Man" to the room. A thrash band had crossed the floor to salute its forebear. Nobody there needed a definition.
The band that the Recording Academy has handed its Best Metal Performance award twice, in February 2000 for a live "Iron Man" taken from the 1998 album Reunion and in January 2014 for "God Is Dead?", is Black Sabbath, and on the institutional record the file was closed long ago. The question, is Black Sabbath heavy metal, survives anyway. It survives because the records are stranger than the reputation.
Asking it is like asking whether a jailer's pattern key is a key. The first key cut for the condemned block, the one every later copy is filed against, still slides into the lock of the cell door and drives the bolt into the frame with the same iron crack as the day it was cut, and every later style from doom to thrash was filed from the riffs of this one band. A copy does not outrank its pattern.
Is Black Sabbath heavy metal? The case against
The prosecution has three counts: the blues the band came out of, the quiet songs it kept recording, and the doubts it voiced about the word itself. All three rest on real records rather than on taste.
The first count is the blues. The 1970 debut carries "Warning", a song by the Aynsley Dunbar Retaliation stretched past ten minutes of jamming, and the band's first single, released on 6 January 1970, was a cover of "Evil Woman", a minor American hit for the Minneapolis group Crow. The style is defined by what it removed from the blues, the shuffle and the long jam above all, as set out under what is heavy metal, and "Warning" keeps both, Iommi's solo in the middle of it wandering for minutes at a time in the old club habit of stretching a song until the set was filled. Ozzy Osbourne's harmonica at the start of "The Wizard", on the same debut, comes out of the same kit. On those tracks, the prosecution wins.
Flute, piano and Mellotron
The second count is the quiet, and to a certain kind of fan it reads as heresy. On Paranoid, "Planet Caravan" hangs between the title track and "Iron Man" like a hammock strung between two gallows, Osbourne's voice fed through a rotating Leslie speaker over congas and a soft jazz guitar solo. Master of Reality has "Solitude", with Tony Iommi on flute. The fourth album went further than either.
Recorded in Los Angeles and released in September 1972, with the band and its manager Patrick Meehan credited as producers, Black Sabbath Vol. 4 set "Changes", a ballad for piano and Mellotron that Iommi taught himself enough piano to write, beside "Laguna Sunrise", an acoustic instrumental with strings, and both beside "Supernaut", a riff that goes through the middle of the record like a bulkhead door slammed shut on a flooding hold. The keyboard player from Yes who turned up at the sessions for the next album and ended up playing on "Sabbra Cadabra" was Rick Wakeman. The same album, Sabbath Bloody Sabbath, carried "Fluff", an acoustic instrumental named in tribute to the disc jockey Alan "Fluff" Freeman, one of the few broadcasters who played the band at all and who had already taken the band's earlier instrumental "Laguna Sunrise" as the theme for his own rock show.
None of it is heavy metal. All of it sits on the same records as the riffs that made heavy metal.
Horns, synthesisers and a word the band did not want
The third count is the one the band wrote itself. By the late 1970s the four men were pulling in every direction at once, and Technical Ecstasy, in 1976, brought in the keyboardist Gerald Woodroffe to push synthesisers up in the mix beside the guitar, and gave Bill Ward his first lead vocal, on "It's Alright", a piano ballad with more of the Beatles in it than of anything from Aston. It stalled at number thirteen in Britain.

Recorded in Toronto and released in September 1978, Never Say Die! put a horn section on the instrumental "Breakout", which lands on a Black Sabbath record like a wedding band marching out onto a firing range, and handed the vocal on "Swinging the Chain" to the drummer for the second album running. Osbourne was gone within months. The band behind him was running out of road.
The words came slowly too. Geezer Butler has recalled, in an account he gave the broadcaster Eddie Trunk and that Far Out Magazine printed in May 2022, that heavy metal first reached the band as an insult, a critic on the road in America writing that the music sounded like a bunch of heavy metal being smashed together. Doom metal presses its own claim from the other side, reading the slowest songs of the first three albums as the opening chapter of a different book, and Candlemass, Saint Vitus and Pentagram built whole careers on the tempo of "Black Sabbath" and "Into the Void". But doom is itself a branch of heavy metal. The claim moves the band from the hall into one of its side rooms, and never out of the building. Both objections are honest. Neither is fatal.
The verdict, and the record that settles it
Take the list of the first heavy metal bands and most of the names on it walked away from the riff for good, into funk, country rock or the pop charts. This band wandered and came back every time, and the proof arrived in April 1980.
The singer brought in from Rainbow to stand where Osbourne had stood was Ronnie James Dio, and Heaven and Hell, produced by Martin Birch and released that month, is as orthodox a heavy metal record as the decade made, "Neon Knights" going through the door at full tilt, "Die Young" swinging between hush and storm, and the title track building seven minutes of riff and voice into a single tower. The album climbed to number nine in Britain. The band whose credentials keep being questioned made the textbook when it had to. It did not need a new name to do it.
The singers changed after that and the style did not. Ian Gillan on Born Again in 1983, Glenn Hughes on Seventh Star in 1986, an album billed as Black Sabbath featuring Tony Iommi, Tony Martin on Headless Cross in 1989 and Dio again on Dehumanizer in 1992: every voice that passed through the band sang over riffs that could be filed nowhere else. The guitarist stayed. So did the weight. On 13, produced by Rick Rubin in 2013 and the band's first number one album in America and its first in Britain since Paranoid, three of the four original members went back to the slow, crushing tempos of 1970, and closed the argument where it had started.
The heirs settled it long before that. The Bay Area band that folded "Sabbra Cadabra" into a medley with "A National Acrobat" on its 1998 covers album Garage Inc. was Metallica, which is to say the biggest heavy metal band in America treated the song Rick Wakeman had played on, piano and all, as scripture. Nobody in that band ever asked the question.
A band that invents a style is allowed to wander off it on a Tuesday. The style is not allowed to disown the band.
Declan Rourke, KaosMetal
So the answer is yes, beyond dispute, with the margins written in. Black Sabbath is heavy metal at the centre of every album from 1970 to 13 in 2013, and the flute, the piano, the horns, the Mellotron and the ten minute blues jam are the margins of a catalogue that no later band has been able to write without. The pedigree runs one way only. How far the word reaches today, and where it stops, comes down to what the heavy metal genre actually covers.