Mata Borrão emerged from Belo Horizonte's extreme metal underground as a side project of members from Death Dealer and later Putrifocinctor, delivering a chaotic blend of grindcore and death metal with lyrics targeting social inequality, religious fanaticism, and political alienation. Their 2014 album 'Assim Já Dizia Augusto dos Anjos' — recorded at Studio Attack in Belo Horizonte — stands as their defining statement, with the lineup of Igor Gabriel on vocals, Leandro Alves on guitars, Vitor Malta on bass, and Thiago Pena on drums.

Matahero is a crossover and thrashcore band from Santiago, Chile, formed in 2003. The band has built a steady discography over more than a decade, including their self-titled debut album in 2008, the EP Idealismo Inoperante in 2011, and the full-length Pensamiento Lateral in 2015 via Malaidea Discos.

Matakabra brought a confrontational edge to northeastern Brazil's extreme metal scene, combining deathcore heaviness with death metal, black metal, and djent elements into a sound driven by deeply political Portuguese-language lyrics. Their 2017 EP 'Marginal' — featuring the tracks 'No Açoite' and 'Mordaça' — addressed racism and systemic oppression head-on, earning the band a place in the Força Metal BR annual compilation and a performance at the long-running Abril Pro Rock festival in Recife.

Matarte is a three-piece metal band from Punta Alta, Buenos Aires, Argentina, formed around 2013, consisting of vocalist Ulises Kaliléc, guitarist/bassist Jonathan Bazan, and drummer Agnatne Ajeivut. The band released their album "Sangra Maldad Eterna" on June 6, 2020, a ten-track record recorded, mixed, and mastered at Tumumu Untungu Home Studio in Punta Alta. Their sound blends melodic death and thrash metal with occult lyrical themes, as heard on tracks like "Dioses Muertos" and "Sacrificio Infernal".

Mate Cosido was a groove metal band from Buenos Aires, Argentina, whose lineup featured vocalist Lito Pared, guitarists Alejandro Venneri and Román Montesi, bassist Gerardo Lucero, and drummer Javier Dorado, who had previously played with Argentine metal legends A.N.I.M.A.L. The band released their self-titled album through EMI in 1996, recorded in June and July of that year and produced alongside Augusto Milharcic. The 12-track record remains their only known release before the band split up.

Maten al Rey is a melodic heavy metal and hard rock band from Quilmes, Buenos Aires, Argentina, composed of vocalist and guitarist Sergio Goddio, bassist Alejandro López, and drummer Leonardo Rodaro. The band — whose name translates as "Kill the King" — released the album "Mar Adentro" in October 2018, produced by Marcelo Vázquez. They operate as an independent act and are listed in Metal Archives under the Argentine power metal scene.

Mathrem is a Death Metal band from Ambato, Tungurahua, Ecuador. Their 2019 release "Profecias y Ruinas" established them as an independent act working within the Ecuadorian underground extreme metal scene. The band operates without label support, self-releasing their material on Bandcamp.

Matricidium plays straight-ahead thrash metal rooted in the aggressive tradition of early Brazilian and US thrash, releasing their debut album 'Rise the Army' in 2012 through MS Metal Records and following it with an expanded European edition in 2014. In October 2015 the band completed their first European tour across nine countries, playing 15 shows in 23 days and establishing themselves beyond the domestic circuit.

Matvey is a traditional heavy metal band from Rosario, Argentina, featuring vocalist Pablo Podesta, guitarist Diego De Santiago, bassist Marcos Sartori, and drummer Mariano Gauna. The band released "Reinando entre colinas" independently in 2012, a Spanish-language epic metal album drawing on Nordic mythology, which was later reissued in 2014 by Electric Punishment Records of Rosario. They shifted toward 1980s US heavy and speed metal influences on their 2019 album "Evil Force and Wild Street", released through Thundersteel Records, and have performed live in both Argentina and Spain.