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.

In the original lineup, King, Hanneman and Araya contributed to the band's lyrics, and all of the band's music was written by King and Hanneman. The band's lyrics and album art, which cover topics such as serial killers, torture, genocide, organized crime, secret societies, occultism, terrorism, religion or antireligion, fascism, racism and war, have generated album bans, delays, lawsuits and criticism from religious groups. However, its music has been highly influential, being cited by many bands as an influence musically, visually and lyrically; the band's third album, Reign in Blood (1986), has been described as one of the heaviest and most influential thrash metal albums.

Slayer released twelve studio albums, three live albums, a box set, six music videos, two extended plays and a cover album. Four of the band's studio albums have received gold certification in the United States. Slayer sold 5 million copies in the United States from 1991 to 2013, according to Nielsen SoundScan. The band has received five Grammy Award nominations, winning one in 2007 for the song "Eyes of the Insane" and one in 2008 for the song "Final Six", both of which were from the album Christ Illusion (2006). After more than three decades of recording and performing, Slayer announced in January 2018 that it would embark on a farewell tour, which took place from May 2018 to November 2019, after which the band disbanded. Slayer later announced some reunion shows in February 2024.