There are at least five artists under this name. Two Black Metal Bands, a Thrash Metal band, a Hardcore Punk Band and an Electronica musician with this Nickname:
#1) Mayhem is a black metal band from Oslo, Norway which was originally formed in 1983, taking strong influence especially from Hellhammer/Celtic Frost, Venom and from earlier Bathory. The name "Mayhem" was taken from the title of the Venom song "Mayhem with Mercy". Much controversy has surrounded the band regarding various murders, suicides, and other forms of violence.