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1990s and early 2000s subgenres and fusions

The era of heavy metal's mainstream dominance in North America came to an end in the early 1990s with the emergence of Nirvana and other grunge bands, signaling the popular breakthrough of alternative rock. Grunge acts were influenced by the heavy metal sound, but rejected the excesses of the more popular metal bands, such as their "flashy and virtuosic solos" and "appearance-driven" MTV orientation.

Glam metal fell out of favor due not only to the success of grunge, but also because of the growing popularity of the more aggressive sound typified by Metallica and the post-thrash groove metal of Pantera and White Zombie. In 1991, Metallica released their album Metallica, also known as The Black Album, which moved the band's sound out of the thrash metal genre and into standard heavy metal. The album was certified 16× Platinum by the RIAA. A few new, unambiguously metal bands had commercial success during the first half of the decade – Pantera's Far Beyond Driven topped the Billboard chart in 1994 – but, "In the dull eyes of the mainstream, metal was dead." Some bands tried to adapt to the new musical landscape. Metallica revamped its image: the band members cut their hair and, in 1996, headlined the alternative music festival Lollapalooza, which was founded by Jane's Addiction singer Perry Farrell. While this prompted a backlash among some longtime fans, Metallica remained one of the most successful bands in the world into the new century.

Like Jane's Addiction, many of the most popular early 1990s groups with roots in heavy metal fall under the umbrella term "alternative metal". Bands in Seattle's grunge scene such as Soundgarden are credited for making a "place for heavy metal in alternative rock", and Alice in Chains were at the center of the alternative metal movement. The label was applied to a wide spectrum of other acts that fused metal with different styles: Faith No More combined their alternative rock sound with punk, funk, metal and hip-hop; Primus joined elements of funk, punk, thrash metal and experimental music; Tool mixed metal and progressive rock; bands such as Fear Factory, Ministry and Nine Inch Nails began incorporating metal into their industrial sound (and vice versa); and Marilyn Manson went down a similar route, while also employing shock effects of the sort popularized by Alice Cooper. Alternative metal artists, though they did not represent a cohesive scene, were united by their willingness to experiment with the metal genre and their rejection of glam metal aesthetics (with the stagecraft of Marilyn Manson and White Zombie – also identified with alt metal – significant, if partial, exceptions). Alternative metal's mix of styles and sounds represented "the colorful results of metal opening up to face the outside world".

In the mid- and late 1990s came a new wave of U.S. metal groups inspired by the alternative metal bands and their mix of genres. Dubbed "nu metal", bands such as Slipknot, Linkin Park, Limp Bizkit, Papa Roach, P.O.D., Korn and Disturbed incorporated elements ranging from death metal to hip-hop, often including DJs and rap -style vocals. The mix demonstrated that "pancultural metal could pay off". Nu metal gained mainstream success through heavy MTV rotation and Ozzy Osbourne's 1996 introduction of Ozzfest, which led the media to talk of a resurgence of heavy metal. In 1999, Billboard noted that there were more than 500 specialty metal radio shows in the U.S., nearly three times as many as 10 years before. While nu metal was widely popular, traditional metal fans did not fully embrace the style. By early 2003, the movement's popularity was on the wane, though several nu metal acts such as Korn or Limp Bizkit retained substantial followings.