'Paranoid' is the second studio album by Black Sabbath. Released in September 1970, it was the band's first LP to top the UK Albums Chart. 'Paranoid' is the album that defined the sound, style and intensity of heavy metal.
 
Led Zeppelin and Deep Purple may have a say in that, but Black Sabbath were much, much heavier. Kurt Cobain always said he wanted Nirvana to be a mixture of the Beatles tunes and Black Sabbath's heaviness.