Kristoffer Rygg, also known as Garm, Trickster G. Rex and God Head, is a Norwegian vocalist, musician and producer known primarily for his work with Ulver, Arcturus, and Borknagar.

Ulver is a Norwegian experimental electronica band founded in 1993, by vocalist Kristoffer Rygg. Their early works, such as debut album Bergtatt, were categorised as folklore-influenced black metal, but the band has since evolved a fluid and increasingly eclectic musical style, blending genres such as experimental rock, electronica, ambient, trip hop, symphonic and chamber traditions, noise, progressive and experimental music into their oeuvre. 1997 marked their international debut with the release of their third album Nattens madrigal through German label Century Media. However, following discord with the label, Rygg formed his own imprint, Jester Records, in 1998.