A one-person DIY project blending thrash, hardcore, and grindcore with a deliberately absurdist sensibility, Marafo de Exú debuted in 2016 with the 16-track album "Diabólico Alcoólico," a chaotic slab of short, fast songs delivered with raw, lo-fi ferocity. The project also released a live recording from Destroy Music Now Fest 3, capturing the same unfiltered intensity in a live setting.

Marbas Valfoerd is a Buenos Aires black metal project that released its debut full-length Primus Omen Op.1 on February 22, 2021. The project also collaborates with fellow Argentine musician Blatt Siro under the name Argiaren, which issued the instrumental release Fragmento 1 in April 2022.

Guitarist Marcelo Souza spent six years in the thrash metal band Attomica (2014–2020), touring across South America before launching a solo instrumental career that draws on metal, neoclassical, blues, and progressive fusion. His 2021 album "Human vs Machine," released through Oversonic Music, features guest appearances from vocalists Mário Pastore and lap steel guitarist Luís Carlini, and explores the tension between human expression and digital dependency.

Marcelo Yakko is an Argentine bassist and composer from Villa Gesell whose output spans more than 15 instrumental albums blending progressive metal, jazz fusion, and Latin influences. His 2018 album Nevada Mortal is a progressive metal concept record inspired by the classic Argentine sci-fi comic El Eternauta, and his 2024 release Yakkosonics features a roster of international collaborators including guitarist Alex Suarez and drummers Nicolas Fernandez Mac Loughlin and Martin Zamorano.

Marco Melo is a progressive metal and shred guitarist from Pernambuco whose catalog blends intricate lead work with collaborative experimentation. His debut EP End of Days (2016) established his direction, and subsequent releases like Transcendent (with Hugo Rioli and Doug Brito) and Drained (with Filipe Soares) showcase a penchant for guest-driven compositions that push the boundaries of technical metal guitar.

Formed in Barbacena, Minas Gerais in 2005 by bassist Delmario Lauriano and guitarist/vocalist Rodrigo Costa, Marmorium Crucis blended gothic doom with deathrock and psychedelic textures, drawing lyrical themes from regional folklore — sanatoriums, cemeteries, and misty streets. Their 2011 demo Le chemin de croix des ames collects nine originals alongside a cover of the Rolling Stones' "Gimme Shelter", capturing the band's phantasmagoric aesthetic before their eventual dissolution.

Marnak is an atmospheric black metal project from Rio Grande do Sul that debuted in 2025 with the EP Xuèyǔ zhī Jì, a four-track release running nearly thirty minutes. The use of Chinese-language titles signals an interest in cross-cultural atmosphere, and the project slots comfortably into the expansive, melancholic end of the Brazilian atmospheric black metal underground.

Marthiria were a thrash metal band from São Luís, Maranhão, active from 2006 until their split in 2010, with a lineup anchored by vocalist/guitarist Andre Nadler and guitarist Rodrigo Lages. They released the EP Sobrevivendo ao Caos (2008), a direct, riff-driven effort in the tradition of Brazilian thrash that earned them a foothold in the local underground before the band disbanded.

Marthirio is a two-piece thrash/crossover band from Santa Fe, Argentina, formed in April 2018 by Matias Echauri (guitars, bass, and vocals) and drummer Lucas Engler. Their debut album Mosh Till Death, recorded at Superyeah Studios and mixed by Anibal Rodriguez at Blazing Hatred Records, was released on August 25, 2021, and includes a cover of Sepultura's "Troops of Doom."