'Paranoid' is a best-selling album from 1970 by which of the following groups?

'Paranoid' was Black Sabbath's only album to top the UK Albums Chart back in 1970 until the release of '13' in 2013. The album contains several of the band's signature songs, including 'Iron Man', 'War Pigs' and the title track, which was the band's only Top 20 hit, reaching number 4 in the UK charts.

In 2017, 'Rolling Stone' magazine considered it the greatest metal album ever.

Black Sabbath were an English rock band formed in Birmingham in 1968 by guitarist Tony Iommi (born 19 February 1948), drummer Bill Ward (born 5 May 1948), bassist Terence Michael Joseph 'Geezer' Butler (born 17 July 1949) and vocalist John Michael 'Ozzy' Osbourne (born 3 December 1948). They are often cited as pioneers of heavy metal music. Heavy metal (or simply metal) is a genre of rock music that developed in the late 1960s and early 1970s, largely in the United Kingdom and United States. With roots in blues rock, psychedelic rock and acid rock, heavy metal bands developed a thick, monumental sound characterized by distortion, extended guitar solos, emphatic beats and loudness.