Mad Billy is a solo grindcore project from Catanduva, São Paulo state, Brazil, launched in 2023 by the multi-instrumentalist known as Billy Grind. The project's debut release, the nine-track EP A Raw Tale Mad Max (2023), was conceived as a tribute to George Miller's Mad Max universe, with Billy Grind handling all instruments, vocals, mixing, and mastering himself.

Mad Chicken are a stoner/grunge metal quintet from Arcos, Minas Gerais, Brazil, formed in 2013, featuring Filipe Xavier on vocals, André Salviano on bass, Pedro Paim on drums, and Daniel Mudo and Carlos Macarrão on guitars. The band released their debut studio album Limestoner in 2017 and followed it with the EP Poultrygeist in September 2022 via Abraxas and Limestone Records, recorded entirely in an analog fashion in three days at ForestLab Studio in Paty do Alferes.

Mad Dog is a heavy metal and hard rock band from Buenos Aires, Argentina, led by guitarist Martín Knye — a veteran of Argentine metal who previously fronted LZ2 (1986–1989) and recorded the country's first neoclassical metal album, El fuego sagrado (1989), before stints in Kamikaze, Magiar, and KZ4. The band features vocalist Javier "Oso" Muñiz, drummer Adrián Micheli, and bassist Diego Magnacca, and released a three-track EP in 2016 ("Dios Del Asfalto," "Huestes," "Mad Dog") followed by the ten-song debut full-length Hell Raising Breed in April 2020. Knye has cited Black Sabbath, AC/DC, and Black Label Society as primary influences, describing the band's sound as "pure, hard, and brutal rock."

Mad Head Machine are a stoner/southern metal band from Joinville, Santa Catarina, Brazil, drawing on heavy metal, stoner rock, and Southern rock influences. Their 2018 release Snakes is a four-track record produced by Calamar Sounds in Florianópolis, featuring tracks such as "Stoner Head" and "Snake's Lair".

Mad Roulette are a heavy metal band from Rio de Janeiro, Brazil, formed in 2014, composed of Marcio Abud on guitar and vocals, Andre "Cheddar" on bass and vocals, and Marcos Soli on drums. The band released the full-length Turn the Wheel in February 2018 through MS Metal Records, delivering nine tracks of straightforward heavy metal with prominent riffs and forceful drumming.

Madhouse is a thrash metal band from Rancagua, in Chile's O'Higgins Region, formed in 2019. The band operates independently within the active Chilean thrash metal underground, drawing on the aggressive traditions of the genre.

Madkill is an old-school thrash metal band from São Paulo, Brazil, formed in 2014 and rooted in the aggressive speed and thrash traditions of the Brazilian scene. The band released their debut album "Mass Destruction" in 2014 and followed it with "Intense Violence" in 2019, a ten-track record described as old school thrash/speed metal with tracks such as "Thrash City" and "Saint Death". They have remained active into the mid-2020s, releasing the politically charged "Protesto" in 2024.

Maelström is a progressive gothic metal band originally from Rio de Janeiro, Brazil, formed in 1994 and one of the longer-running acts in the country's gothic metal underground. The band released a self-titled debut album in 2001 and a second full-length, "Decline of the West", in 2006 through Force Majeure Records, which also issued a special double-CD edition bundling both releases. Guitarist, keyboardist, and vocalist Alexandre Cegalla has been a central figure in the band throughout its existence.

Maerebat is a Buenos Aires black metal act featuring Lord Abductum on music and Satani Lamentatio on lyrics, with drums handled by Favio Guzman. The band released their debut four-track recording "Amos del Caos" in April 2024, having tracked it the previous year before editing and releasing it independently.