On Through the Night, Def Leppard's debut album, established the band as one of the leading lights of the New Wave of British Heavy Metal. While possessing the tight, controlled attack of comrades Judas Priest and Iron Maiden, Def Leppard was uninterested in the fantastic, menacing, and sometimes gothic themes of those bands; instead, On Through the Night is a collection of working-class hard rock anthems informed by the big, glittering hooks of glam rock. It may lack the detailed production and more pop-oriented songwriting of later efforts, but it's also arguably their heaviest album, and some Leppard fans prefer this sound.