The band, whose name goes back to Venom's song Mayhem with Mercy, was formed in 1984 by Jørn "Necrobutcher" Stubberud, Kjetil "'Morbid' Manheim" Manheim and Øystein Aarseth (who initially operated under the pseudonym "Destructor" and then changed to "Euronymous") renamed) founded in Langhus. In the logo there is the addition The True (engl. 'The True'), since several bands with the name Mayhem existed. Initially, the band played Venom and Metallica tracks before writing their own material. At first the band was mainly influenced by Venom, as well as Bathory, Hellhammer, Sodom and Destruction. Necrobutcher cites Motörhead and Venom as the most important influences. In 1985 they gave their first live performance in front of 400 people with the singer Eirik "Messiah" Nordheim. In 1986 they recorded the demo Pure Fucking Armageddon, in which Euronymous and Necrobutcher shared the vocals.Their early lyrics were downright violent, similar to the splatter lyrics of Death Metal. Like many other previous Black Metal releases, their demos were also characterized by extremely poor recording quality: The vocals on Pure Fucking Armageddon could hardly be heard, which is why the English magazine Metal Forces assumed that none had been recorded.