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.

Bad Taste is a death/thrash metal band from Porto Alegre, Rio Grande do Sul, Brazil, formed in 2017. They operate out of the South Brazilian underground, a region with a strong tradition of extreme metal, playing aggressive thrash rooted in the death metal aesthetic. The band remains active as an independent act.

Badhead is a thrash/crossover hardcore band from Brasília, Brazil, formed in 2015. Blending the pit-ready aggression of hardcore punk with the riff-driven attack of thrash metal, they contribute to the capital's vibrant underground crossover scene. The band remains active as an independent act.

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.

Balrog is a speed/thrash metal band from Villa Ballester, Buenos Aires, formed around 2000. The band released the album "No nos Detendrán" in 2014 and has featured vocalist and bassist Omar "BuBBa" Fernández alongside guitarist Lautaro Medina as core members of their long-running lineup.

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.