Heavy metal music
Critics disagree over who can be thought of as the first heavy metal band. Most credit either Led Zeppelin or Black Sabbath, with American commentators tending to favour Led Zeppelin and British commentators tending to favour Black Sabbath, though many give equal credit to both. A few commentators—mainly American—argue for other groups including Iron Butterfly, Steppenwolf or Blue Cheer. Deep Purple, the third band in what is sometimes considered the "unholy trinity" of heavy metal (Black Sabbath, Led Zeppelin, and Deep Purple), despite being slightly older than Black Sabbath and Led Zeppelin, fluctuated between many rock styles until late 1969 when they took a heavy metal direction.
Metallica
Metallica is an American heavy metal band. The band was formed in 1981 in Los Angeles, California by drummer Lars Ulrich and vocalist/guitarist James Hetfield, and has been based in San Francisco, California for most of its career. The group'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 Hetfield and Ulrich, longtime lead guitarist Kirk Hammett and bassist Robert Trujillo. Guitarist Dave Mustaine (who went on to form Megadeth) and bassists Ron McGovney, Cliff Burton and Jason Newsted are former members of the band.