Member:
1992- Ulver - vocals  
1993-2003 Arcturus - vocals  
1995-1997 Borknagar - vocals  
2005- Head Control System - vocals  
Guest musician:
1995 Gehenna - vocals  
2000 Fleurety - vocals  
2001 Zyklon - vocals  
2001 Star Of Ash - vocals  
2001 SCN - vocals  
2002 Kåre João - vocals  
2003 Virus - vocals  
2003 Magenta - vocals  
2003 The Gathering - vocals  
2006 Ihsahn - vocals  
2006 Solefald - vocals  
2007 Professor Fate - vocals  
2008 Star Of Ash - vocals  
2009 Nidingr - vocals  
2010 Dimmu Borgir - vocals  
2011 Virus - vocals  
2012 Nidingr - vocals  


Personal information

Born on: 09.09.1976

Kristoffer Rygg, also known as Garm, G. Wolf, Trickster G., Fiery G. Maelstrom and recently also God Head is a Norwegian vocalist, musician and producer widely known for his multi-range singing styles in black metal and beyond.

Born September 9th, 1976 in Oslo, Rygg was 16 years old when he formed Ulver, which was considered one of the most groundbreaking bands of the genre as well as an instigator for related subcategories such as folk metal and avant garde metal.

In addition, Rygg had also been a vocalist for Borknagar (1995-1997) and Arcturus (1993-2003), both of which comprise many notable musicians from the early Norwegian Black Metal scene. He was also the one responsible for introducing Borknagar to the singer who replaced him, ICS Vortex, when he parted ways with the band.

Rygg possesses a wide range of vocal textures and styles, ranging from falsettos, baritone, and even black metal style rasps and shrieks, though performed with an extra venomous intensity not found in many other vocalists.

He currently runs Jester Records, an underground label specializing in experimental and strange music, including Ulver, which has since taken to a musical direction almost impossible to classify. He has also performed as a guest for a very large list of other artists, including Gehenna, Hagalaz Runedance, Aphrodisiac, Kåre João, Magenta, The Gathering, Emperor, Merzbow, Solefald and Sunn O))) among others.

Most recently Rygg has been collaborating with multi-talented musician/ producer Daniel Cardoso (ex-SiriuS and Re:aktor among others) in a band previously called SinDRomE (i.e. Severe Damage of Reason and Equilibrium) until recently when the two of them decided to change the band name to Head Control System. The music is heavy rock/metal, described by the band as "heavy rock with progressive edges, alternative feeling and a strong visual cinematic component." Their first full-length was released April 4th, 2006 under the name Murder Nature through The End Records, home to such bands as Ulver, Voivod, Dissection, Sleepytime Gorilla Museum, Estradasphere and many other bands.