Although in the beginning of the 1970s both Black Sabbath and the American Pentagram performed a kind of music that can be considered proto-doom, neither band is generally considered as an actual doom metal band. From the late 1970s to mid 1980s, bands such as Trouble, Saint Vitus and Witchfinder General contributed much to the formation of doom metal as a distinct genre. The form of music played by these artists can be described as being rooted in both the music of Black Sabbath and the New Wave of British Heavy Metal, especially the band Witchfinder General. The slowness of their music is often also seen as a reaction to the constantly increasing speed of contemporary thrash metal and speed metal. Doom metal first became widely popular with Sweden's Candlemass, who are hailed in the mainstream metal press as one of the most important and influential doom metal bands; their 1986 album Epicus Doomicus Metallicus is considered a genre-defining release (at least within the epic subgenre of doom metal). According to the proponents of the classic doom metal style, the most descriptive doom band would be Saint Vitus, who released their self-titled debut album in 1984 - two years before doom metal as a genre was recognised in the mainstream metal press.
Doom metal developed further in the early 1990s, when a number of bands started combining the slow, melancholic, doom metal style that was pioneered in the 1980s with influences from death metal and other forms of extreme metal, including growled vocals. The first band to combine these styles may have been the heavily Celtic Frost-influenced Winter, although this style is generally associated with and made popular within mainstream heavy metal by three British bands: Paradise Lost, My Dying Bride and Anathema. Nowadays, the original brand of doom metal with clean vocals is usually labelled "classic doom", whereas the later developed styles which involve growled vocals are commonly called "death/doom", more recently even "nu-doom".
During the 1990s the doom metal genre developed further styles, although classic doom and death/doom have remained central to the present. A number of bands, such as The Gathering and Theatre of Tragedy took the music of Paradise Lost, got rid of some of the slowness and started experimenting with female vocals*, thereby helping to create the generally more accessible genre of gothic metal. Although this genre is generally considered to be influenced by doom metal, it is not usually considered a subgenre of doom metal: certain elements, such as the slowness and the emphasis on heavy riffing, are often absent. However, other bands emphasised doom metal's distinctive features and created extreme subgenres such as funeral doom and drone doom, pioneered by Thergothon and Earth respectively.
It has been argued that a nexus exists between doom metal, stoner metal and psychedelic music, although each of these genres have developed on their own. The stoner metal of bands like Kyuss, Monster Magnet and Queens of the Stone Age shares with doom metal a heavy sound and a strong Black Sabbath influence, but generally has a different objective: whereas doom metal aims for melancholia, stoner metal aims for a groovy and psychedelic sound. A number of doom metal bands, however, such as (later) Cathedral, Electric Wizard and Darkage have combined doom metal with psychedelic influences, thereby creating a style which can be considered a hybrid form of doom metal and psychedelic rock.
*It should be noted, however, that Paradise Lost themselves made some use of female vocals on their second album, Gothic, in 1990.
Doom metal - Wormphlegm, Tyranny, Candlemass.