B on Reason is a heavy/thrash metal band from Pernambuco, Brazil, formed in 2021. The project spans multiple releases including albums titled The Mission, Endless Siege, and The Empire of Lost Souls, carving out a self-described universe of metal, game, and multimedia content. Their sound sits in the classic heavy metal and thrash tradition rooted in the Northeast Brazilian underground.

Baba de Sheeva is a thrash/crossover band from Goiânia, Goiás, Brazil, bringing the fast and irreverent spirit of the genre to the Central-West metal scene. Formed with themes revolving around life, religion, drinking, and weed, the band released the CD-R É Triste O Destino Da Maioria Dos Homens in 2011 and has remained an active presence in the Goiânia underground. Their sound blends the aggression of old-school thrash with the punk energy of crossover.

Backstroke is a thrash metal band from Brasília, Brazil, formed in 2019. Operating out of the capital's underground scene, the band channels straightforward, aggressive thrash in the Bay Area and Brazilian tradition. They remain active as an independent act in the Brasília metal community.

Bacteria is a heavy/thrash metal band from San José, Entre Ríos, Argentina, active since 1999. The band appeared on the 2009 compilation "2dos. Puro Metal" released by Kodigo Rojo Records out of Concordia, Entre Ríos, one of the few regional metal labels documenting the underground scene in that province.

Badtrip Surfdeath is an instrumental power trio from São Paulo, Brazil, active since 2008 and coined the term 'surfdeath' to describe their collision of hardcore, grind blasts, black metal riffs, and psychedelic textures. The trio of Rodrigo Chã (guitar), Manéu Junqueira (bass), and Marcus Dentão (drums) released their self-titled debut in 2011 followed by Badtrip Surfdeath II in 2013, both recorded in São Paulo. Their entirely wordless approach lets the genre-blurring density of the music speak for itself.

Bandanos were a thrash/crossover band from São Paulo who emerged from the city's hardcore punk veteran pool with a mission to revive the raw energy of bands like D.R.I., Suicidal Tendencies, and Excel. Over their active years they released multiple albums — including "Nobody Brings My Coffin Until I Die" (2014) and several splits — and mounted an extensive European tour in 2009 spanning 28 shows across 11 countries. They split up in the 2010s after building a loyal following in the underground crossover circuit.

Bastardos are a heavy/thrash metal band from Campana, Buenos Aires province, featuring guitarist and vocalist Leandro Maidana, guitarist Marcos Campos, bassist Facundo Bougnet, and drummer Cristian Basilio. The band released their album Visiones de un Mundo en Decadencia in July 2020, an eight-track record that includes tracks such as "Sacerdotes de la Miseria" and "Nada Quedará." Not to be confused with the Buenos Aires-based Bastardös, this band carves out a rawer, more street-level approach to Argentine heavy metal.

Bastardös are a thrash metal band from the La Paternal neighborhood of Buenos Aires, built around vocalist and guitarist Tommy Doglioli alongside drummer Federico Pinzolas, guitarist Camilo Ibañez, and bassist Maximiliano López. The band earned a reputation in the Argentine underground for visceral live shows and lyrics grounded in everyday street-level hardship. Their 2024 album Entierrö, a 27-minute slab of aggressive thrash, was formally presented at Uniclub in Buenos Aires to mark the record's official release.

Basttardz are a crossover thrash/hardcore band from São Luís, Maranhão, formed in 2020 during the Covid-19 pandemic. Taking cues from Ratos de Porão, Municipal Waste, and D.R.I., the band sings entirely in Portuguese and channels working-class Brazilian rage on their debut album Brasil com Z, which tackles labor exploitation and social inequality in eight tracks recorded in a garage spirit.