Building from the musical structure of thrash metal and early black metal, death metal emerged during the mid 1980s. It was mainly inspired by thrash metal and early black metal acts like Slayer, Kreator, Celtic Frost, and Venom. Along with the band Death and its frontman Chuck Schuldiner, who is often referred to as "the father of death metal", bands like Possessed, Obituary and Morbid Angel are often considered pioneers of the genre. In the late 1980s and early 1990s, death metal gained more media attention as popular record labels like Earache and Roadrunner began to sign death metal bands at a rapid rate. Since then, death metal has diversified, spawning a variety of subgenres.

The setup most frequently used within the death metal genre is two guitarists, a bass player, a vocalist and a drummer almost universally using two bass drums or a double bass drum pedal.[citation needed] Although this is the standard setup, bands have been known to occasionally incorporate other instruments such as electronic keyboards.[citation needed]

The genre is often identified by fast, highly distorted and downtuned guitars, played with techniques such as palm muting and tremolo picking. The percussion is usually aggressive, and powerful; blast beats, double bass and exceedingly fast drum patterns frequently add to the complexity of the genre.

Death metal is known for its abrupt tempo, key, and time signature changes, as well as fast and complex guitar and drumwork. Death metal may include chromatic chord progressions and a varied song structure, rarely employing the standard verse-chorus arrangement. These compositions tend to emphasize an ongoing development of themes and motifs.

Death metal vocals are often guttural roars, grunts, snarls, and low gurgles colloquially known as death growls. The style is sometimes referred to as Cookie Monster vocals, tongue-in-cheek, because of the similarity with the popular Sesame Street character of the same name. Although often criticized, death growls serve the aesthetic purpose of matching death metal's violent lyrical content.

The lyrical themes of death metal often invoke slasher film-stylized violence, but may also extend to topics like Satanism, anti-religion, Occultism, mysticism, philosophy, social commentary. Although violence may be explored in various other genres as well, death metal elaborates on the details of extreme acts, including mutilation, dissection, torture, rape and necrophilia. Sociologist Keith Kahn-Harris commented this apparent glamorization of violence may be attributed to a "fascination" with the human body that all people share to some degree, a fascination which mixes desire and disgust. Heavy metal author Gavin Baddeley also stated there does seem to be a connection between "how acquainted one is with their own mortality" and "how much they crave images of death and violence" via the media. Additionally, contributing artists to the genre often defend death metal as little more than an extreme form of art and entertainment, similar to horror films in the motion picture industry. This rationalization has brought such musicians under fire from activists internationally, who claim that this is often lost on a large number of adolescents, who are left with the glamorization of such violence without social context or awareness of why such imagery is stimulating.

According to Alex Webster, bassist of Cannibal Corpse, "The gory lyrics are probably not, as much as people say, [what's keeping us] from being mainstream. Like, 'Death metal would never go into the mainstream because the lyrics are too gory?' I think it's really the music, because violent entertainment is totally mainstream."

There are several theories how the term "death metal" originated. One theory is the name originates from an early pioneer of the genre, Death. A Florida journalist explained to his readers Death play their own kind of metal: "Death's Metal". Others contest Death is not the origin, but the harsh vocals and morbid lyrical content generally inspired the genre. Another possible origin is a fanzine called Death Metal, started by Thomas Fischer and Martin Ain of Hellhammer and Celtic Frost. The name was later given to the 1984 compilation Death Metal released by Noise Records. The term might also have originated from other recordings. Possessed's 1984 demo is called Death Metal, and a song with the same name is featured on their 1985 debut album Seven Churches. A demo released by Death in 1984 is called Death by Metal.

English heavy metal band Venom crystallized the elements of what later became known as thrash metal, death metal and black metal, with their 1981 album Welcome to Hell. Their dark, blistering sound, harsh vocals, and macabre, proudly Satanic imagery proved a major inspiration for extreme metal bands. Another highly influential band, Slayer, formed in 1981. Although the band was a thrash metal act, Slayer's music was more violent than their thrash contemporaries Metallica, Megadeth and Exodus. Their breakneck speed and instrumental prowess combined with lyrics about death, violence, war and Satanism won Slayer a rabid cult following. According to Allmusic, Slayer's third album Reign in Blood "inspired the entire death metal genre". It had a big impact on the genre leaders.

Possessed, a band that formed in the San Francisco Bay Area during 1983, was attributed by Allmusic as having a Slayer influence on their 1985 album, Seven Churches. Although Possessed's brand of metal resembled Slayer's fast and Satanic thrash metal style, they are often cited as the "first" death metal band. This is largely because of the grunted vocals which set the stage for death metal's breakaway from thrash metal. The 1984 demo Death Metal and 1985 album Seven Churches are regarded as their most influential material.