A death metal and grindcore band from Kyustendil, Bulgaria, operating in the extreme underground of the country's metal scene. Documented in the Encyclopaedia Metallum, they represent one of the few grindcore-oriented acts to emerge from the southwestern Bulgarian metal community.

Mass Hypnosis is a band from Zagreb, Croatia, formed in 2014, having evolved from metalcore and melodic death metal into industrial, groove, and nu-metal. Their stylistic evolution reflects an adventurous creative journey across heavy music styles.

Mass Hysteria is a thrash metal act from Holmestrand in Vestfold, active since 2020. The band delivers aggressive, crowd-inciting thrash from the Oslofjord region.

Mass Infection is a Greek extreme metal band from Livadia with a catalog including 'Atonement For Iniquity,' 'The Age Of Recreation,' 'For I Am Genocide,' and 'Shadows Became Flesh.' The band maintains an active presence across streaming platforms and their official website massinfection.net.

Mass Insanity is a melodic heavy metal band from Bremen, Germany, active since 2011. Their sound delivers the classic melodic heavy metal formula with an emphasis on strong hooks and powerful arrangements from northern Germany's thriving metal community.

Mass Madness is a thrash/death metal band from Moscow, Russia, formed in 2011. They forge aggressive extreme metal at the crossroads of death and thrash.

Mass Murder Squad is a black and death metal band from Greece, formed in 2020. They channel violent extremity through the convergence of black and death metal.

Mass of the Heretic is a black/death metal band from Moscow, Russia, formed in 2016. They forge extreme metal at the fierce intersection of black and death metal.

Mass Ritual Murder are a death/black metal band from Austria, formed in 2021 as an independent underground act. The band is registered in the Encyclopaedia Metallum and operates without label affiliation, channelling the raw tradition of extreme metal into their self-produced output. They represent the newer wave of Austrian extreme metal acts building a presence through digital platforms.