Blacktorch is a Buenos Aires instrumental progressive metal band led by guitarist Juan Polastri alongside co-founder Gabriel Pozzo on drums. Their debut album Gravitational Collapse, released on October 24, 2023, uses the physics of gravitational collapse as a conceptual framework, blending modern metal with elements of jazz and rock.

Blades of Steel is a heavy metal band from São Paulo, Brazil, fronted by vocalist Yara Haag. Drawing influence from Judas Priest, Accept, and Mercyful Fate, the band released a self-titled track in 2024 and subsequently signed with Alone Records of Greece for wider international distribution.

Blair is a heavy metal band from Aracaju, Sergipe, Brazil, one of the few metal acts to emerge from the northeastern Brazilian state. The band sings in Portuguese and has been described as evoking the spirit of 1980s hard rock and heavy metal, with well-crafted guitar work and a melodic sensibility that connects to classic rock traditions.

Blakk Market is a thrash/melodic death metal band from Florianópolis, Santa Catarina, Brazil, formed by former members of Despotic alongside vocalist Fernando Melleu. The band released a demo, "Hateful Affection," followed by their debut full-length "Self-Improvement: Suicide" in 2011, a ten-track record dealing with themes of personal integrity and nihilism. They were active within the southern Brazilian metal circuit before going on hold around 2017.

BlankWar is a progressive thrash metal band from Bragança Paulista, in the interior of São Paulo state, Brazil, formed in 2016. The band released a self-titled debut album in 2016 and subsequently put out a single titled "BloodSuckers," carving out a niche within Brazil's active underground thrash scene.

Blasart is a black/death metal band from Santiago, Chile, founded by guitarist Eduardo Vera, who had previously played in the brutal death metal group Orategod. The band debuted with the full-length The Art of Blasphemy in 2008, followed by the Rebellion Abyss Chaos EP in 2014 and the Depravatus EP in 2022; their sophomore full-length Depravatus Christianis Sacris was released through Czech label Lavadome Productions in March 2026. Their anti-Christian lyrical themes are matched by a sound that blends black metal atmosphere with death metal weight and sharp thrash metal aggression.

Blasfemador is a speed/thrash metal band from Fortaleza, Ceará, Brazil, known for combining the aggression of 1980s extreme metal with horror and occult themes, and for performing entirely in Portuguese. Their discography includes the full-length "Cosmofobia" (2021) and the 2026 album "Malleus Maleficarum," which has been described as their most ambitious release to date. The band is not to be confused with a separate Blasfemador project from Alfenas, Minas Gerais.

Blasphemaniac is a black/thrash metal band from Atibaia, São Paulo, Brazil, playing what they describe as old school black speed metal rooted in blasphemy, satanism, and witchcraft. The band has released several records including "Lust Possession" (2021), "Bestial Occult Ceremony" (2022), and "Night of the Necromancer" (2023) via Black Hearts Records and Death Defier Productions. They performed at the Brazilian Harmageddon 2024 festival in São Paulo alongside international acts such as Sabbat.

Blasphematorium is a heavy/speed/black metal band from São Paulo, Brazil, formed around 2020 and signed to Tales from the Pit Records. The band released a self-titled debut album in February 2020, drawing on occult and blasphemous themes in the vein of classic South American extreme metal. Their sound fuses the drive of speed metal with raw black metal atmosphere.