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.
Warner Music Group
WEA was an early champion of heavy metal rock music. Several such bands, including three major British pioneers Led Zeppelin, Black Sabbath, and Deep Purple, were all signed to WEA's labels, at least in the United States. Among the earliest American metal acts to be signed to WEA were Alice Cooper, Montrose, and Van Halen.