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.
Black metal
A notable black metal group in England was Cradle of Filth, who released three demos in a black/death metal style with symphonic flourishes, followed by a studio album, which featured a then-unusual hybrid style of black and gothic metal. The band then abandoned black metal for gothic metal, becoming one of the most successful extreme metal bands to date. John Serba of AllMusic commented that their first album "made waves in the early black metal scene, putting Cradle of Filth on the tips of metalheads' tongues, whether in praise of the band's brazen attempts to break the black metal mold or in derision for its 'commercialization' of an underground phenomenon that was proud of its grimy heritage". Some black metal fans did not consider Cradle of Filth to be black metal. When asked if he considers Cradle of Filth a black metal band, vocalist Dani Filth said he considers them black metal in terms of philosophy and atmosphere, but not in other ways. Another English band called Necropolis never released any music, but "began a desecratory assault against churches and cemeteries in their area" and "almost caused Black Metal to be banned in Britain as a result". Dayal Patterson says successful acts like Cradle of Filth "provoked an even greater extremity [of negative opinion] from the underground" scene due to concerns about "selling out".