Metallica is an American thrash metal band from Los Angeles, California, formed in 1981.
The band was founded when James Hetfield responded to an advertisement that drummer Lars Ulrich had posted in a local newspaper. Metallica's line-up has primarily consisted of Ulrich, rhythm guitarist and vocalist James Hetfield, and lead guitarist Kirk Hammett, while having had a number of bassists (Ron McGovney, Cliff Burton, and Jason Newsted). The bassist is currently Robert Trujillo. The band's original lead guitarist, before Hammett, was current Megadeth guitarist and lead vocalist Dave Mustaine.
Metallica's early releases included fast tempos, instrumentals, and aggressive musicianship that placed them as one of the "big four" of the thrash metal subgenre alongside Slayer, Megadeth, and Anthrax, during the genre's development into a popular style. The band earned a growing fan base in the underground music community and critical acclaim, with the 1986 release Master of Puppets described as one of the most influential and "heavy" thrash metal albums. The band achieved substantial commercial success with their eponymous fifth album (also known as The Black Album), which debuted at number one on the Billboard 200. With this release the band expanded its musical direction resulting in an album that appealed to a more mainstream audience.