Speed metal is a sub-genre of heavy metal music originating in the late 1970s and early 1980s that was the direct musical progenitor of thrash metal. When speed metal first emerged as a genre, it increased the tempos that had been used by early heavy metal bands such as Led Zeppelin, Black Sabbath, and Deep Purple, while retaining their melodic approaches. Many elements of speed metal are rooted in the music of UK's NWOBHM bands while fusing their stylistic approach with the music of 1970's punk rock.
The term speed metal has been broken down and specified with other terms under heavy metal (typically thrash metal, power metal, and to a lesser extent, black metal) and is often succeeded by such terms when an artist's sound or style is specifically defined . The term 'speed metal' was also used in a very broad sense by some glam metal and NWOBHM groups during the 1980s. Many Japanese bands from the 1980s to the present can also be described as speed metal, largely due to the success of X Japan.
There were earlier efforts with a similar style including Led Zeppelin's Communication Breakdown, and also Deep Purple's "Speed King" from their 1970 album In Rock and "Fireball" from their 1971 album Fireball..
The first major use of the term speed metal, however, dates to the late 1970s radio show on KROQ in Los Angeles. The show was hosted by former-Runaways member Ann Boleyn, and featured the fast-paced sounds of Judas Priest, Rush, and Deep Purple. The show was known as Speed Metal at Midnight.
Motörhead added primitive speed metal elements to their brand of heavy metal since their inception in mid-1970s, heavily influenced by punk, later quickly evolving and developing their characteristic speed metal style with classic releases such as 1979 album Overkill and yet another one, Ace of Spades, released the following year. Eponymous song "Overkill" from the former is among the first examples of steady and fast double bass drum tracks used in a metal song, with technique soon becoming common for diverse metal genres.
Newer bands also began to emerge on the scene. The NWOBHM movement had reached its zenith at this stage and many bands embraced speed metal, notably Venom, who built on Motorhead's style to achieve a raw, harsh atmosphere. NWOBHM bands such as Iron Maiden and Raven produced a number of speed metal songs as well, such as "Aces High" and "Invaders" by the former.
The German heavy metal band Accept also introduced speed metal elements into their sound at the start of the decade. The song "Fast as a Shark" on their 1982 album Restless and Wild is an example of Accept's speed metal ideas, and is also notable for the extreme speed (for the time) of it's double bass drumming and for its heavy palm muted riffing. Accept's influence on the German heavy metal scene was unquestionably huge. Bands such as Running Wild, Grave Digger, Helloween, Rage and Paradox built upon the fast tempos of Accept to form the foundations of German speed metal.
Bands who would later develop into thrash originally had their music deeply rooted in speed metal. Slayer’s debut album Show No Mercy, Metallica's debut album Kill 'Em All, Anthrax’s debut album Fistful of Metal, Megadeth's debut album Killing Is My Business... And Business Is Good! and Overkill’s debut album Feel the Fire, as well as many other early albums by thrash metal bands, contained speed metal elements (inspired by the NWOBHM) that were combined with archetypical thrash metal riffs. These bands would eventually allow thrash motifs to dominate their music resulting in the thrash metal explosion of the mid 80s.
However, several bands concentrated on refining their speed metal sound instead of veering in this new musical direction. Notable examples include Agent Steel and Exciter, two bands who, at the time, chose to remain speed metal.