Def Leppard are an English hard rock/heavy metal band from Sheffield, who formed in 1977 as part of the New Wave of British Heavy Metal movement. Largely on the strength of their albums Pyromania and Hysteria, Def Leppard became one of the top-selling rock bands throughout the 1980s, selling over 65 million albums worldwide, including over 35 million in the United States alone. Def Leppard are ranked #31 on VH1's "Greatest Artists of Hard Rock".

By the release of the Hysteria album, the band had developed a distinctive sound featuring heavy drums and effects-laden guitar sounds overlaid with a multi-layered wall of husky, harmonised vocals. Def Leppard is one of only five rock bands with two original albums selling over 10 million copies each in the US. The others are The Beatles, Led Zeppelin, Pink Floyd, and Van Halen.