[5] As a young boy, he was an avid fan of hard rock band Kiss and his first heavy metal album was Creatures of the Night, which made him feel "immortal".

[7] Immortal was formed in 1991 by Abbath and Demonaz, alongside other former members of the extreme metal bands Old Funeral and Amputation.

At various times throughout the band's history, Abbath has been the lead vocalist, bassist, guitarist, keyboardist, drummer, and lyricist, due to the difficulties of upholding a stable line-up.

During Immortal's early years, Abbath originally served as the band's vocalist, bassist and studio drummer, while Demonaz played guitar.

After the release of Blizzard Beasts in 1997, Demonaz was diagnosed with acute tendinitis, and was consequently forced to quit as guitarist, but remained as lyricist and band manager.

The band's performance at Wacken Open Air in 2007 was recorded and filmed for the release of the 2010 video album The Seventh Date of Blashyrkh.

[13] The band released their debut album Between Two Worlds in 2006 and performed their only concert at that year's Hole in the Sky festival in Bergen.

Nicola "Morrigan" Trier (of Aeternus) filled in on bass in his absence while Bratseth handled vocal duties.

Abbath served as an inspiration for the appearance of the character Lars Ümlaüt from the video game series Guitar Hero.

Jester King Brewery in Austin, Texas has an Abbath-inspired character on the label of their Black Metal Imperial stout.