Testament is an American thrash metal band from Berkeley, California. Formed in 1983 under the name Legacy, the band's current lineup comprises guitarists Eric Peterson and Alex Skolnick, lead vocalist Chuck Billy, drummer Gene Hoglan, and bassist Steve Di Giorgio. Since its inception, Testament has had numerous lineup changes, leaving Peterson as the only constant member. Billy replaced original singer Steve "Zetro" Souza (who left the band to join Exodus as the replacement of Paul Baloff) in 1986, prior to the recording of their first studio album, The Legacy, and has been a member of the band since. He and Peterson are the only members to appear on all of Testament's studio albums. Testament is often credited as one of the most popular and influential bands of the thrash metal scene, as well as one of the leaders of the second wave of the genre in the late 1980s. They have also been referred to as one of the "big eight" of thrash metal, along with Metallica, Megadeth, Slayer, Anthrax, Exodus, Overkill and Death Angel. The band has sold over 1.4 million albums in the United States since the beginning of the SoundScan era and over 14 million copies worldwide. To date, Testament has released twelve studio albums (one of which is a collection of re-recorded songs), four live albums, five compilation albums, twelve singles and three DVDs. After signing to Atlantic Records, and changing their name from Legacy to Testament in 1986, they released their debut album The Legacy in 1987, and broke into the U.S. mainstream with its follow-up album The New Order (1988). Their next four studio albums—Practice What You Preach (1989), Souls of Black (1990), The Ritual (1992) and Low (1994)—were also successful, with the former of the three entering the Top 100 on the Billboard 200 chart. Over the course of its career, Testament has experienced several resurgences of popularity, with their last two studio albums—Dark Roots of Earth (2012) and Brotherhood of the Snake (2016)—entering the Top 20 on the Billboard 200, and has toured consistently. The band will release their thirteenth studio album, Titans of Creation, on April 3, 2020.

Gary Wayne Holt (born May 4, 1964) is an American guitarist from the San Francisco Bay Area. He is a guitarist, the bandleader, and the main songwriter for the American thrash metal band Exodus and is also a guitarist for the American thrash metal band Slayer, in which he took over duties for original guitarist Jeff Hanneman, who died in 2013. After guitarist Tim Agnello left Exodus in 1981, Holt joined the band and has been the main songwriter and the most senior member of the group ever since. Following Kirk Hammett's 1983 departure from Exodus to join Metallica, Holt kept the band going and for many years, he and Rick Hunolt were referred to as the Exodus' "H-Team" guitar players. Holt is the only member of Exodus who has played on every album.

Death Angel is an American thrash metal band from Daly City, California, initially active from 1982 to 1991 and again since 2001. Death Angel has released eight studio albums, two demo tapes, one box set and two live albums. The band has gone through several line-up changes, leaving guitarist Rob Cavestany as the only constant member; he and vocalist Mark Osegueda (who joined the group in 1984) are the only members of Death Angel to appear on all of their studio albums. Death Angel is often referred to as one of the key bands in the Bay Area thrash metal movement of the 1980s, and secured opening slots at club venues that decade, including opening for their peers Megadeth, Metallica, Slayer, Exodus, Testament, Overkill, D.R.I., Mercyful Fate and Possessed. They are also often credited as one of the leaders of the second wave of thrash metal movement, as well as one of the "big eight" of the genre (along with Metallica, Megadeth, Slayer, Anthrax, Testament, Exodus and Overkill).