Shadow King was an American hard rock supergroup. It was formed in 1990, by former Foreigner lead singer Lou Gramm, future Def Leppard guitarist Vivian Campbell, drummer Kevin Valentine of Donnie Iris and the Cruisers, and bass player Bruce Turgon who later joined Foreigner with Gramm after the split of Shadow King.
Vivian Campbell and Bruce Turgon both also played with Lou Gramm as a solo artist previous to Shadow King, with Campbell playing on Long Hard Look, and Turgon playing on Ready or Not and Long Hard Look.
They released a self-titled album in 1991. Although plans were made for a tour, they performed only once, at the Astoria Theatre in London, England, on December 13, 1991. Rick Seratte joined the band for this performance with backup vocals and playing keyboards. Shortly afterward, Vivian Campbell announced he was leaving Shadow King to join Def Leppard. Although replacements were considered, the band members eventually went their separate ways, with Gramm rejoining Foreigner in 1992 bringing in Turgon along with him.