Reign in Blood is the third studio album and the major label debut by the American thrash metal band Slayer. It was released on 7 October 1986 through Def Jam Recordings. The album was the band's first collaboration with record producer Rick Rubin, whose input helped the band's sound evolve. Reign in Blood was universally well received by both critics and fans, and was responsible for bringing Slayer to the attention of a mainstream metal audience. Kerrang! magazine described the record as "the heaviest album of all". Alongside Anthrax's Among the Living, Megadeth's Peace Sells... but Who's Buying? and Metallica's Master of Puppets, Reign in Blood helped define the sound of the emerging US thrash metal scene in the 1980s, and has remained influential subsequently.
Reign in Blood's release was delayed because of concerns regarding its graphic artwork and lyrical subject matter. The opening track, "Angel of Death", which refers to Josef Mengele and describes acts, such as human experimentation, that Mengele committed at the Auschwitz concentration camp, provoked allegations of Nazism. However, the band stated numerous times they do not condone Nazism, and are merely interested in the subject. The album was Slayer's first to enter the Billboard 200; the release peaked at number 94, and was certified Gold on 20 November 1992.