Paranoid

Released in Britain on Vertigo on 18 September 1970 and in the United States on Warner Bros. on 7 January 1971. Much of the material had been worked up in Zurich club dates in late 1969. The album was meant to be called War Pigs, but the label changed the title to that of the single, which Butler and the band had written quickly to fill the record. Butler wrote its lyrics in about two hours.

It reached number 1 in Britain, the band's only chart-topper there until 13, and number 12 in the United States, and sold four times Platinum there. AllMusic's Steve Huey gave it five stars and said it defined the sound and style of heavy metal more than any other record in rock history. Robert Christgau gave it a C minus, Pitchfork gave it 9.5, and Rolling Stone placed it first in its 2017 list of metal albums and 139th in its 2020 list of the 500 greatest albums.

Planet Caravan is the record's quiet turn. Butler wrote its lyric about floating through the universe with a lover, Osbourne sang through a Leslie speaker, engineer Tom Allom played the piano, Iommi overdubbed flute onto the reversed multitrack master, and Ward played congas. Fairies Wear Boots is the only song on the album with a lyric by Osbourne, and band lore ties it to a fight with skinheads after a gig.

Writing in Pitchfork in 2018, Grayson Haver Currin read the record as a document of its time and place: the Vietnam war, nuclear annihilation and working-class Birmingham. He wrote that Vertigo heard a hit where the band had written filler, and that the label renamed the album Paranoid after the single. Butler said the sleeve, a soldier photographed by Marcus Keef, was bad enough when the album was to be called War Pigs and made no sense at all once it was Paranoid. Currin heard the verses of Hand of Doom pointing toward doom metal and Rat Salad anticipating math-rock.