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.
Thrash metal
In 1981, a Southern California band Leather Charm wrote a song entitled "Hit the Lights". Leather Charm soon disbanded and the band's primary songwriter, vocalist/rhythm guitarist James Hetfield met drummer Lars Ulrich through a classified advertisement. Together, Hetfield and Ulrich formed Metallica, the first of the "Big Four" thrash bands, with lead guitarist Dave Mustaine, who would later form Megadeth, another of the "Big Four" originators of thrash, and bassist Ron McGovney. Metallica later relocated to the San Francisco Bay Area. McGovney was replaced with Cliff Burton, and Mustaine was later replaced with Kirk Hammett. "Hit the Lights" was featured on their first studio album, "Kill 'Em All", released in mid–1983.