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.
Heavy hardcore
The New York hardcore band Killing Time is considered one of the earliest heavy hardcore bands. Killing Time released its debut album "Brightside" in 1989. The album has been compared to the heavy metal band Metallica. During the late 1980s and other heavy hardcore bands, such as Sheer Terror, Madball, Judge, and Maximum Penalty, also emerged. Madball, one of the bands that helped launch the heavy hardcore genre with its crossover thrash-esque style, released its debut album "Set It Off" in 1994. Jason Anderson of AllMusic noted the album's "raw lyrics and thick guitar grooves". Sheer Terror used obvious heavy metal influences in its music, using, according to Eduardo Rivadavia of AllMusic, "staccato picking, slow-as-molasses power chords," and "double kick drums". According to Ryan Downey of AllMusic, Judge added "a thick, metallic guitar crunch to the by then standard manic, angst-ridden, and ragged neo-punk sound of the mid- to late-'80s underground hardcore scene."