Mitsein is a symphonic metal outfit from Brasília built around the guitar work of Jeff Oliveira and the vocals of Cristienne Graciano. The band draws broadly from power, progressive, and melodic metal and has released singles and EPs since 2020, including a contribution to the Motim Underground compilation with the track "Revenge" in 2021.

Moana is a deathcore band from the interior of São Paulo state delivering heavy, Portuguese-language extreme music. The band released the album "Oceano Paralelo" and has steadily built a catalog since their early 2010s demos, including the track "Cordilheira da Discórdia."

Mochica is a solo pagan black metal project from Lima, Peru, created by the musician Viracocha as a tribute to the ancient Moche civilization of northern Peru. Active since 2002 and released through Pagan Warriors Records, the project blends raw black metal aggression with pre-Columbian Andean themes, with the 2024 demo "Ritual Conqueror" showcasing that indigenous-inspired lyrical focus.

Modorra was an experimental death metal project from Igrejinha, Rio Grande do Sul that pushed the genre into confrontational, noise-adjacent territory. The band released the album "Solar Anus" and a split 12" before splitting up, leaving behind a catalog that sat at the intersection of death metal brutality and avant-garde provocation.

Molitium is a heavy and progressive metal band from Santa Catarina whose 2018 debut album "Progeny" laid out a sound rooted in melodic guitar work and dynamic song structures. The record featured guest appearances from Marcelo Braga across multiple tracks, giving it a collaborative texture uncommon for a debut release.

Moloch is a black metal band from Recife who have sustained an underground output since 2007, releasing a sprawling catalog of splits, EPs, and albums across more than a decade. They have collaborated with international acts including Hermóðr, Nocturnal Depression, I Shalt Become, and Wedard, situating themselves firmly within the global depressive and raw black metal underground.

Monasterium was a death/doom/gothic metal band from Teresina active in the late 1990s, releasing the full-length "Innocent Rise" on Demise Records in 1999 and a demo titled "Inviolable" in 1998. Their sound blended the heavy melodic sensibility of gothic doom with death metal weight, placing them among the more ambitious extreme acts to emerge from the Piauí underground.

Monje is a stoner/doom metal band from Buenos Aires, active since 2016, featuring guitarist Diego Petullo, vocalist Matias Ibañez, bassist Lucas Scardamaglia, and drummer Diego Hernandez. The band has released three studio albums — Monje (2018), Druga Dimenzija (2020), and Culto al Fin de los Tiempos (2023) — alongside a live album, Igual de Macabro: Live Bunker (2022). Their later work incorporates dissonant harmonies, blast beats, and black and death metal influences alongside the core doom sound.

Mono Histeria is a Curitiba outfit blending progressive, doom, and stoner metal into a dense, riff-driven sound. The band released "Volume 1" in 2022 and has tracks such as "Instinto" and "Primata" available on streaming platforms, pointing toward a sound influenced by the heavier end of the psychedelic and doom rock spectrum.