M-19 is a thrash metal band from Porto Alegre, Rio Grande do Sul, Brazil, originally formed in 1989, drawing influence from Slayer, Destruction, Kreator, and Sepultura. After releasing demo tapes "Manifest of Insanity" (1989) and "When a Promise Is Broken" (1994) and a decade-long hiatus, the band returned to release the full-length "Mission: Destroy" in 2013 and "Sic Semper Tyrannis" in 2019, the latter celebrating thirty years of their founding.

M.A.S.A.C.R.E is a heavy metal institution founded in Lima, Peru in the mid-1980s, regarded as one of the most representative metal bands in South America. The band has shared stages with acts including Iron Maiden, Paul Di'Anno, and Rata Blanca, and has appeared on international tribute albums honoring Argentine legends V8 and Colombian band Kraken. Their catalog includes four full-lengths, with the thrash-oriented albums "Demoledor" (2001) and "Versos del inframundo" (2016) among their later work.

M.D.K. is a brutal death metal and grindcore band from Jundiaí, São Paulo, Brazil, formed in 1997 by core members Thales Zago (guitars/vocals), André Lazarini (drums/bass), and Boca (vocals). The trio released three studio albums—"Splatterguts" (2005), "Cuntanasia" (2009), and "Into the Pussymorgue" (2012)—alongside a prolific run of splits with international goregrind acts including Malignant Tumour, Kadaverficker, and Rotten Penetration.

M.H.X's Chronicles is a melodic death metal band from São Paulo, Brazil, founded by guitarist and vocalist Murillo Henrique Xavier, whose initials give the band its name. The project expanded into a full quartet with Raphael Carvalho on drums, Michel Oliveira on guitars, and Wallace Ribeiro on bass, releasing the EP "The Preface" (2013) and the fifty-six-minute debut album "Infinite Ocean" in 2015, recorded at Sputnik Home Studio.

M1 Garand is a Brazilian raw black metal solo project formed in 2022, with all instruments, vocals, mixing, and mastering handled by a member operating under the alias Soldier 'Charles' of 101st Airborne Division. The project carries an explicit anti-Nazi and anti-NSBM stance, reflected in its debut EP "The Party is Over Kraut" (2022), which blends World War II themes with sardonic humor directed at fascist ideology.

M26 is an atmospheric doom/death metal band from Pelotas, Rio Grande do Sul, Brazil, formed in 2021. The band incorporates female vocals into their heavy, melancholic sound, and released their debut album "Misantropia" in February 2021 through Bandcamp.

M60 in Hands is a raw black metal and noise solo project from Catanduva, São Paulo, Brazil, formed in 2023 and operated entirely by Billy Grind, who handles all instruments and vocals. The project released the EP "Infinity War in My Head" in 2023 and appeared on the 2024 split "Old Skull Black Metal" alongside Night Goat on Podreira Records, paying tribute to first-wave black metal acts Von and Root.

M67 is a groove metal and hardcore band from Manaus, Amazonas, Brazil, founded in 2017 by Naveca Ogro and Gabriel Alladoh and named after the M67 fragmentation grenade. The band draws on Amazonian folklore for lyrical content, explored in their EP "Agouros Amazônicos," which features tracks themed around legends of the Brazilian Amazon including the single "Mapinguari Algoz" (2020).

Macabro is a speed metal/punk band from São Paulo, Brazil, featuring Ruan Pablo on vocals, Gui Disanti on guitar, Naum Prado on bass, and Uriel Franco on drums. The band channels working-class protest energy alongside themes of Satanism and anarchy, and released the album "Mensageiros do Caos" (Messengers of Chaos) in December 2023.