Steinar Sverd Johnsen is a Norwegian keyboardist and composer. Sverd plays keyboards and synthesizers in Arcturus and was also the main composer for the band. He formed the band with Marius Vold (Mortem, Stigma Diabolicum of Thorns, and Jan Axel Blomberg of Mayhem in 1987, originally under the moniker Mortem. The band split up in April 2007, but reformed in 2011.