Avant-garde metal is a subgenre of heavy metal music loosely defined by use of experimentation and innovative, avant-garde elements, including non-standard and unconventional sounds, instruments, song structures, playing styles, and vocal techniques. Avant-garde metal is influenced by progressive rock and extreme metal, particularly death metal, and is closely related to progressive metal. Some local scenes include Los Angeles, the San Francisco Bay Area, Boston, and Seattle in the United States, Oslo in Norway, and Tokyo in Japan.

Extreme metal is a loosely defined umbrella term for a number of related heavy metal music subgenres that have developed since the early 1980s. It has been defined as a "cluster of metal subgenres characterized by sonic, verbal, and visual transgression".