Metallica is an American heavy metal band. It was formed in Los Angeles in 1981 by vocalist and guitarist James Hetfield and drummer Lars Ulrich, and has been based in San Francisco for most of its career. The band's fast tempos, instrumentals and aggressive musicianship made them one of the founding "big four" bands of thrash metal, alongside Megadeth, Anthrax and Slayer. Metallica's current lineup comprises founding members and primary songwriters Hetfield and Ulrich, longtime lead guitarist Kirk Hammett and bassist Robert Trujillo. Guitarist Dave Mustaine, who formed Megadeth after being fired from Metallica, and bassists Ron McGovney, Cliff Burton and Jason Newsted are former members of the band. 

Metallica first found commercial success with the release of its third album, "Master of Puppets" (1986), which is cited as one of the heaviest metal albums and the band's best work. The band's next album," ...And Justice for All" (1988), gave Metallica its first Grammy Award nomination.  After experimenting with different genres and directions in subsequent releases, Metallica returned to its thrash metal roots with its ninth album, "Death Magnetic" (2008), which drew similar praise to that of the band's earlier albums. The band's eleventh and most recent album, "72 Seasons", was released in 2023.