Anthrax is an American thrash metal band from New York City, formed in 1981 by rhythm guitarist Scott Ian and bassist Dan Lilker. The group is considered one of the leaders of the thrash metal scene from the 1980s and is part of the "Big Four" of the genre, along with Metallica, Megadeth and Slayer. They were also one of the first thrash metal bands to emerge from the East Coast. The band's current lineup consists of Scott Ian, drummer Charlie Benante, bassist Frank Bello, vocalist Joey Belladonna and lead guitarist Jonathan Donais. Anthrax's lineup has changed numerous times over their career, leaving Ian as the only constant member of the band. Ian and Benante are the only two members to appear on all of Anthrax's albums, while Bello has been a member of Anthrax since 1984, replacing Lilker.

Slayer is an American thrash metal band from Huntington Park, California, formed in 1981 by guitarists Kerry King and Jeff Hanneman, drummer Dave Lombardo and bassist/vocalist Tom Araya. Slayer's fast and aggressive musical style made them one of the "big four" bands of thrash metal, alongside Metallica, Megadeth, and Anthrax. Slayer's current lineup consists of King, Araya, drummer Paul Bostaph and guitarist Gary Holt, who initially joined as a touring member in 2011 before joining the band permanently after Hanneman's death in 2013. Drummer Jon Dette was also a member of the band.