Hysteria is the fourth studio album by English rock band Def Leppard, released on 3 August 1987 through Mercury Records. It is Def Leppard's best-selling album to date, selling over 20 million copies worldwide, including 12 million in the US, and spawning seven hit singles. The album charted at number one on both the Billboard 200 and the UK Albums Chart.
Hysteria was produced by Robert John "Mutt" Lange. The title of the album was thought up by drummer Rick Allen, referring to his 1984 car accident, the amputation of his arm, and the ensuing worldwide media coverage surrounding it. It is the last album to feature guitarist Steve Clark before his death, although songs co-written by him would appear on the band's next album, Adrenalize.