Bruthus is a crossover thrash/heavy metal band formed around 2017–2018 in Nova Friburgo, Rio de Janeiro state, Brazil. Influenced by 1980s and 90s metal and rock, the band sings in Portuguese and has released the EP "O Sacode" (2018) and the full-length "Comigo Não" (2019), sharing stages with acts such as Noturnall and Edu Falaschi.

Bruto is a thrash metal band from Gama, a satellite city of Brasília, Brazil, with roots going back to the mid-2000s. The band performs in Portuguese and blends thrash metal aggression with rock and roll energy, releasing the album "Mundo Destruído" and becoming the first metal band to win the Gama Popular Music Festival (FMPG).

Brutta is a blackened death metal band formed in 2022, featuring São Paulo-based drummer Gledson Gonçalves alongside guitarist/vocalist Adriano Ribeiro (Athemon) and bassist Tom MacLean (ex-Haken). The band released their self-titled debut album in June 2022, a high-speed eight-track assault exploring themes of emptiness, hatred, and religion, followed by the album "Horror" in 2025.

Bríi is an atmospheric black metal, ambient, and electronic project based in Brasília, Brazil, formed in 2020 by musician Caio Lemos, who also records under names including Kaatayra and Vauruvã. The project released the critically noted album "Último Ancestral Comum" in 2023, issued on vinyl by Season of Mist and digitally through Flowing Downward, blending raw black metal blast beats with trance, club electronics, and post-rock atmospheres. Bríi has drawn international attention for its genre-defying fusion of Brazilian sonic identity and extreme metal.

Buaiteoir is a folk metal band from Recife, Pernambuco, Brazil, active since around 2013. The band is distinctive for building their sound around Celtic folk instruments including the tin whistle, bodhrán, and hurdy-gurdy, releasing the EP "Tionscnamh" in 2014 and the single "Caoineadh" in 2017.

Bubonic Cult is a Brazilian raw black metal project formed in 2016, playing lo-fi, orthodox black metal with a harsh, unpolished aesthetic. Their debut release "Negative Aura of Satanic Energy" (2016) is a four-track demonstration of stripped-down, cult black metal with themes of negative spiritual energy.

Buccal Defecation is a brutal death metal band from Quilmes in the Buenos Aires province of Argentina, active in the local extreme underground since at least 2002. The band released a Demo in 2002, the Vaginal Rotten EP in 2011, and the full-length Testament of Brutality in 2014 through Grinder Cirujano Records, and also appeared on the split 3 Ways of Perversity alongside fellow Argentine acts Annihilate and Butcher.

Budasses is a stoner/doom metal project from Villa Lo Errazuriz, Maipú, formed from the ashes of the band Sahumerio. The group released their self-titled demo in 2012 through Proyecto Sepulcro, and later appeared on a 2021 split with Saturno titled "Kura Kütral Ko," tagging their sound as acid weed metal and doom stoner.

Buena Muerte is a death metal band from Florencio Varela in the Buenos Aires metropolitan area of Argentina, featuring guitarist and vocalist Favio Leguizamon alongside bassist Jose Manuel Araujo and drummer Hector Benito Paz. The band released the Dios Es Sádico EP in 2018 and the full-length album Catalepsia in 2024, building a steady presence in Argentina's underground death metal scene over two decades.