There are multiple artists that perform under the name Valve:
1) Generalized moniker for music used in games by Valve Corporation
2) Finnish electronic music project
3) Brazilian rock band
4) French sludge band
5) British grunge band

1) Valve Corporation, also known as Valve Software, is an American video game developer, publisher, and digital distribution company headquartered in Bellevue, Washington. It is the developer of the software distribution platform Steam and the Half-Life, Counter-Strike, Portal, Day of Defeat, Team Fortress, Left 4 Dead, and Dota series.

Kelly Bailey is the former in-house composer for Valve Corp, while Mike Morasky is the current.
The soundtrack for Portal and Portal 2, while primarily composed by Morasky, is credited to Aperture Science Psychoacoustics Laboratory with licensed music by Jonathan Coulton and The National whereas DOTA 2 and Team Fortress 2 are credited to Valve Studio Orchestra.

Valve was founded in 1996 by former Microsoft employees Gabe Newell and Mike Harrington. Their debut product, the PC first-person shooter Half-Life, was released in 1998 to critical acclaim and commercial success, after which Harrington left the company. In 2003, Valve launched Steam, which accounted for around half of digital PC game sales by 2011. By 2012, Valve employed around 250 people and was reportedly worth over US$3 billion, making it the most profitable company per employee in the United States. In the 2010s, Valve began developing hardware, such as the Steam Machine, a brand of gaming PCs, as well as the HTC Vive and Valve Index virtual reality headsets.

2) A collaboration between Sami Määttälä and Joni Autio, from Finland. Sami started his musical experiences sometime around 1996, with computer software called trackers. Joni has always been keen to different kinds of music. As he hasn't been producing as much as Sami, he has a sheer talent in writing lyrics. Valve was born in September 2006, when Sami had almost finished his new track, that didn't quite fit to be released under his other guises.

Sites: Discogs, MySpace and http://ValveMusic.net (official)

3) A Brazilian rock band consisting of Vitoka (guitar), Rafael Ramos (guitar), Gabriel (bass), Lupercio (song) and Duduw (drums).

4) A French sludge band with elements of doom metal and hardcore from Paris
Sites: Bandcamp, Tumblr

5) A British grunge band from London (Album: Pulling Legs Off Flies, 1994)
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