Øystein Aarseth (Norwegian: [ˈœ̂ʏstæɪn ˈôːʂɛt]; 22 March 1968 – 10 August 1993), better known by his stage name Euronymous, was a Norwegian musician. Euronymous was a founder of and central figure in the early Norwegian black metal scene. He was a co-founder and guitarist of the Norwegian black metal band Mayhem and was the only constant member from the band's formation in 1984 until his death in 1993. He was also founder and owner of the extreme metal record label Deathlike Silence Productions and record shop Helvete.
Euronymous professed to being a Theistic Satanist and was known for making extreme misanthropic statements. He presented himself as leading a militant cult-like group known as the "Black Metal Inner Circle".
In August 1993, he was murdered by fellow musician and former bandmate Varg Vikernes.