Hellhammer was a Swiss extreme metal band from Nürensdorf, active from 1982 to 1984. Although the band's sound and style were heavily criticized and poorly reviewed during their active years, they have been widely praised in retrospect and are often regarded as a key influence on black metal. In June 1984, Hellhammer disbanded but two of its members soon formed the influential extreme metal band Celtic Frost.

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".