Extreme metal is a loosely defined umbrella term for a number of related heavy metal music subgenres that have developed since the early 1980s. The term usually refers to a more abrasive, harsher, underground, non-commercialized style or sound nearly always associated with genres like black metal, death metal, doom metal, thrash metal and sometimes speed metal.

Though many extreme sub-styles not very well known to mainstream music fans, as extreme metal is by definition counterculture, extreme metal has influenced an array of musical performers inside and outside of heavy metal.

"Extreme" can be meant to describe any of the following traits: music (whether it is intended to be faster, more aggressive, abrasive or "heavier" than other metal styles), lyrics (dealing with darker, more sensational topics and themes), vocals (which often use guttural, harsh or abrasive singing), or appearance and stage demeanor (using corpse paint, Satanic or occult imagery). The "extreme" label is most commonly applied to bands whose music is extreme; for example, few would consider Kiss or Alice Cooper to be extreme metal, though they could be considered to employ "extreme" elements in their appearance and stage demeanor for their time.

Sam Dunn (born 20 March 1974 either in Victoria, British Columbia, Canada, Toronto, Ontario, Canada or Stroud, England) is a Canadian musician, film director, and anthropologist whose work focuses on the culture of heavy metal. Together with Scot McFadyen, Dunn owns the Toronto based production company Banger Films, Inc.

Dunn's first film, co-directed with Scot McFadyen and Jessica Wise, was released in 2005. The film follows Dunn on a journey to document the origins, culture and appeal of heavy metal. It also explores the themes of heavy metal- violence, death, religion and Satanism, gender and sexuality.

Released in 2008, Sam directed a new film, titled Global Metal. In the film, directors Scot McFadyen and Sam Dunn set out to discover how the West’s most maligned musical genre – heavy metal – has impacted the world’s cultures beyond Europe and North America. The film follows metal fan and anthropologist Sam Dunn on a whirlwind journey through Asia, South America and the Middle East as he explores the underbelly of the world’s emerging extreme music scenes — from Indonesian death metal to Israeli Oriental metal and Chinese black metal to Iranian thrash metal, etc. The film reveals a worldwide community of metalheads who are not just absorbing metal from the West – they are transforming it, and creating a new form of cultural expression in societies dominated by conflict, corruption and mass-consumerism.